diff --git a/lib/fluent/plugin/output.rb b/lib/fluent/plugin/output.rb
index 54dbbeb5e0..976ff1002c 100644
--- a/lib/fluent/plugin/output.rb
+++ b/lib/fluent/plugin/output.rb
@@ -1275,52 +1275,57 @@ def update_retry_state(chunk_id, using_secondary, error = nil)
 
           unless @retry
             @retry = retry_state(@buffer_config.retry_randomize)
+
             if @retry.limit?
-              # @retry_max_times == 0, fail imediately by the following block
-            else
-              if error
-                log.warn "failed to flush the buffer.", retry_times: @retry.steps, next_retry_time: @retry.next_time.round, chunk: chunk_id_hex, error: error
-                log.warn_backtrace error.backtrace
-              end
-              return
+              handle_limit_reached(error)
+            elsif error
+              log_retry_error(error, chunk_id_hex, using_secondary)
             end
+
+            return
           end
 
           # @retry exists
 
-          if @retry.limit?
-            if error
-              records = @buffer.queued_records
-              msg = "failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue."
-              log.error msg, retry_times: @retry.steps, records: records, error: error
-              log.error_backtrace error.backtrace
-            end
-            @buffer.clear_queue!
-            log.debug "buffer queue cleared"
-            @retry = nil
+          # Ensure that the current time is greater than or equal to @retry.next_time to avoid the situation when
+          # @retry.step is called almost as many times as the number of flush threads in a short time.
+          if Time.now >= @retry.next_time
+            @retry.step
           else
-            # Ensure that the current time is greater than or equal to @retry.next_time to avoid the situation when
-            # @retry.step is called almost as many times as the number of flush threads in a short time.
-            if Time.now >= @retry.next_time
-              @retry.step
-            else
-              @retry.recalc_next_time # to prevent all flush threads from retrying at the same time
-            end
-            if error
-              if using_secondary
-                msg = "failed to flush the buffer with secondary output."
-                log.warn msg, retry_times: @retry.steps, next_retry_time: @retry.next_time.round, chunk: chunk_id_hex, error: error
-                log.warn_backtrace error.backtrace
-              else
-                msg = "failed to flush the buffer."
-                log.warn msg, retry_times: @retry.steps, next_retry_time: @retry.next_time.round, chunk: chunk_id_hex, error: error
-                log.warn_backtrace error.backtrace
-              end
-            end
+            @retry.recalc_next_time # to prevent all flush threads from retrying at the same time
+          end
+
+          if @retry.limit?
+            handle_limit_reached(error)
+          elsif error
+            log_retry_error(error, chunk_id_hex, using_secondary)
           end
         end
       end
 
+      def log_retry_error(error, chunk_id_hex, using_secondary)
+        return unless error
+        if using_secondary
+          msg = "failed to flush the buffer with secondary output."
+        else
+          msg = "failed to flush the buffer."
+        end
+        log.warn(msg, retry_times: @retry.steps, next_retry_time: @retry.next_time.round, chunk: chunk_id_hex, error: error)
+        log.warn_backtrace(error.backtrace)
+      end
+
+      def handle_limit_reached(error)
+        if error
+          records = @buffer.queued_records
+          msg = "Hit limit for retries. dropping all chunks in the buffer queue."
+          log.error msg, retry_times: @retry.steps, records: records, error: error
+          log.error_backtrace error.backtrace
+        end
+        @buffer.clear_queue!
+        log.debug "buffer queue cleared"
+        @retry = nil
+      end
+
       def retry_state(randomize)
         if @secondary
           retry_state_create(
diff --git a/lib/fluent/plugin_helper/retry_state.rb b/lib/fluent/plugin_helper/retry_state.rb
index 7851fd61ea..82e5689af3 100644
--- a/lib/fluent/plugin_helper/retry_state.rb
+++ b/lib/fluent/plugin_helper/retry_state.rb
@@ -44,6 +44,8 @@ def initialize(title, wait, timeout, forever, max_steps, randomize, randomize_wi
 
           @timeout = timeout
           @timeout_at = @start + timeout
+          @has_reached_timeout = false
+          @has_timed_out = false
           @current = :primary
 
           if randomize_width < 0 || randomize_width > 0.5
@@ -98,7 +100,7 @@ def calc_next_time
               naive
             end
           elsif @current == :secondary
-            naive = naive_next_time(@steps - @secondary_transition_steps + 1)
+            naive = naive_next_time(@steps - @secondary_transition_steps)
             if naive >= @timeout_at
               @timeout_at
             else
@@ -123,7 +125,15 @@ def step
             @current = :secondary
             @secondary_transition_steps = @steps
           end
+
           @next_time = calc_next_time
+
+          if @has_reached_timeout
+            @has_timed_out = @next_time >= @timeout_at
+          else
+            @has_reached_timeout = @next_time >= @timeout_at
+          end
+
           nil
         end
 
@@ -135,7 +145,7 @@ def limit?
           if @forever
             false
           else
-            @next_time >= @timeout_at || !!(@max_steps && @steps >= @max_steps)
+            @has_timed_out || !!(@max_steps && @steps >= @max_steps)
           end
         end
       end
@@ -159,13 +169,13 @@ def naive_next_time(retry_next_times)
         def calc_max_retry_timeout(max_steps)
           result = 0
           max_steps.times { |i|
-            result += calc_interval(i + 1)
+            result += calc_interval(i)
           }
           result
         end
 
         def calc_interval(num)
-          interval = raw_interval(num - 1)
+          interval = raw_interval(num)
           if @max_interval && interval > @max_interval
             @max_interval
           else
@@ -175,7 +185,7 @@ def calc_interval(num)
               # Calculate previous finite value to avoid inf related errors. If this re-computing is heavy, use cache.
               until interval.finite?
                 num -= 1
-                interval = raw_interval(num - 1)
+                interval = raw_interval(num)
               end
               interval
             end
diff --git a/test/plugin/test_output_as_buffered_retries.rb b/test/plugin/test_output_as_buffered_retries.rb
index f3a08e877f..1fd0307500 100644
--- a/test/plugin/test_output_as_buffered_retries.rb
+++ b/test/plugin/test_output_as_buffered_retries.rb
@@ -140,13 +140,13 @@ def get_log_time(msg, logs)
 
       retry_state = @i.retry_state( @i.buffer_config.retry_randomize )
       retry_state.step
-      assert_equal 1, (retry_state.next_time - now)
-      retry_state.step
       assert_equal (1 * (2 ** 1)), (retry_state.next_time - now)
       retry_state.step
       assert_equal (1 * (2 ** 2)), (retry_state.next_time - now)
       retry_state.step
       assert_equal (1 * (2 ** 3)), (retry_state.next_time - now)
+      retry_state.step
+      assert_equal (1 * (2 ** 4)), (retry_state.next_time - now)
     end
 
     test 'does retries correctly when #write fails' do
@@ -332,7 +332,7 @@ def get_log_time(msg, logs)
       @i.emit_events("test.tag.3", dummy_event_stream())
 
       logs = @i.log.out.logs
-      assert{ logs.any?{|l| l.include?("[error]: failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue.") } }
+      assert{ logs.any?{|l| l.include?("[error]: Hit limit for retries. dropping all chunks in the buffer queue.") } }
     end
 
     test 'output plugin give retries up by retry_max_times, and clear queue in buffer' do
@@ -409,7 +409,7 @@ def get_log_time(msg, logs)
       @i.emit_events("test.tag.3", dummy_event_stream())
 
       logs = @i.log.out.logs
-      assert{ logs.any?{|l| l.include?("[error]: failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue.") && l.include?("retry_times=10") } }
+      assert{ logs.any?{|l| l.include?("[error]: Hit limit for retries. dropping all chunks in the buffer queue.") && l.include?("retry_times=10") } }
 
       assert{ @i.buffer.queue.size == 0 }
       assert{ @i.buffer.stage.size == 1 }
@@ -607,7 +607,7 @@ def get_log_time(msg, logs)
       logs = @i.log.out.logs
 
       target_time = Time.parse("2016-04-13 18:35:31 -0700")
-      target_msg = "[error]: failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue."
+      target_msg = "[error]: Hit limit for retries. dropping all chunks in the buffer queue."
       assert{ logs.any?{|l| l.include?(target_msg) } }
 
       log_time = get_log_time(target_msg, logs)
@@ -695,7 +695,7 @@ def get_log_time(msg, logs)
       @i.emit_events("test.tag.3", dummy_event_stream())
 
       logs = @i.log.out.logs
-      assert{ logs.any?{|l| l.include?("[error]: failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue.") && l.include?("retry_times=10") } }
+      assert{ logs.any?{|l| l.include?("[error]: Hit limit for retries. dropping all chunks in the buffer queue.") && l.include?("retry_times=10") } }
 
       assert{ @i.buffer.queue.size == 0 }
       assert{ @i.buffer.stage.size == 1 }
@@ -743,7 +743,7 @@ def get_log_time(msg, logs)
 
       assert(@i.write_count == 1)
       assert(@i.num_errors == 1)
-      assert(@i.log.out.logs.any?{|l| l.include?("[error]: failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue.") && l.include?("retry_times=0") })
+      assert(@i.log.out.logs.any?{|l| l.include?("[error]: Hit limit for retries. dropping all chunks in the buffer queue.") && l.include?("retry_times=0") })
       assert(@i.buffer.queue.size == 0)
       assert(@i.buffer.stage.size == 1)
       assert(@i.buffer.queue.all?{|c| c.empty? })
diff --git a/test/plugin/test_output_as_buffered_secondary.rb b/test/plugin/test_output_as_buffered_secondary.rb
index ae774b7455..b12bb154a3 100644
--- a/test/plugin/test_output_as_buffered_secondary.rb
+++ b/test/plugin/test_output_as_buffered_secondary.rb
@@ -874,7 +874,7 @@ def dummy_event_stream
       end
 
       logs = @i.log.out.logs
-      assert{ logs.any?{|l| l.include?("[error]: failed to flush the buffer, and hit limit for retries. dropping all chunks in the buffer queue.") } }
+      assert{ logs.any?{|l| l.include?("[error]: Hit limit for retries. dropping all chunks in the buffer queue.") } }
 
       assert{ now >= first_failure + 60 }
     end
diff --git a/test/plugin_helper/test_retry_state.rb b/test/plugin_helper/test_retry_state.rb
index 4edd41bdf9..b61e5e35db 100644
--- a/test/plugin_helper/test_retry_state.rb
+++ b/test/plugin_helper/test_retry_state.rb
@@ -18,6 +18,21 @@ class Dummy < Fluent::Plugin::TestBase
     helpers :retry_state
   end
 
+  class RetryRecord
+    attr_reader :retry_count, :elapsed_sec, :is_secondary
+    def initialize(retry_count, elapsed_sec, is_secondary)
+      @retry_count = retry_count # This is Nth retryment
+      @elapsed_sec = elapsed_sec
+      @is_secondary = is_secondary
+    end
+
+    def ==(obj)
+      @retry_count == obj.retry_count &&
+      @elapsed_sec == obj.elapsed_sec &&
+      @is_secondary == obj.is_secondary
+    end
+  end
+
   setup do
     @d = Dummy.new
   end
@@ -75,6 +90,7 @@ class Dummy < Fluent::Plugin::TestBase
     override_current_time(s, s.next_time)
     s.step
     assert_equal s.timeout_at, s.next_time
+    s.step
     assert s.limit?
   end
 
@@ -100,7 +116,6 @@ class Dummy < Fluent::Plugin::TestBase
     assert_equal 5, i
     override_current_time(s, s.next_time)
     s.step
-    assert_equal (s.current_time + 3), s.next_time
     assert s.limit?
   end
 
@@ -164,7 +179,9 @@ class Dummy < Fluent::Plugin::TestBase
     assert s.secondary?
 
     s.step
-    assert_equal s.timeout_at, s.next_time
+    assert_equal s.timeout_at, s.next_time # 100
+
+    s.step
     assert s.limit?
   end
 
@@ -202,7 +219,7 @@ class Dummy < Fluent::Plugin::TestBase
     while i < 300
       s.step
       assert_equal i, s.steps
-      assert_equal (dummy_current_time + 0.1 * (2 ** (i - 1))), s.next_time
+      assert_equal (dummy_current_time + 0.1 * (2 ** i)), s.next_time
       assert !s.limit?
       i += 1
     end
@@ -218,22 +235,22 @@ class Dummy < Fluent::Plugin::TestBase
     assert_equal 0, s.steps
     assert_equal (dummy_current_time + 0.1), s.next_time
 
-    # 0.1 * (2 ** (10 - 1)) == 0.1 * 2 ** 9 == 51.2
-    # 0.1 * (2 ** (11 - 1)) == 0.1 * 2 ** 10 == 102.4
+    # 0.1 * 2 ** 9 == 51.2
+    # 0.1 * 2 ** 10 == 102.4
     i = 1
-    while i < 11
+    while i < 10
       s.step
       assert_equal i, s.steps
-      assert_equal (dummy_current_time + 0.1 * (2 ** (i - 1))), s.next_time, "start:#{dummy_current_time}, i:#{i}"
+      assert_equal (dummy_current_time + 0.1 * (2 ** i)), s.next_time, "start:#{dummy_current_time}, i:#{i}"
       i += 1
     end
 
     s.step
-    assert_equal 11, s.steps
+    assert_equal 10, s.steps
     assert_equal (dummy_current_time + 100), s.next_time
 
     s.step
-    assert_equal 12, s.steps
+    assert_equal 11, s.steps
     assert_equal (dummy_current_time + 100), s.next_time
   end
 
@@ -249,32 +266,28 @@ class Dummy < Fluent::Plugin::TestBase
     assert_equal 0, s.steps
     assert_equal (dummy_current_time + 1), s.next_time
 
-    # 1 + 1 + 2 + 4 (=8)
+    # 1 + 2 + 4 (=7)
 
     override_current_time(s, s.next_time)
     s.step
     assert_equal 1, s.steps
-    assert_equal (s.current_time + 1), s.next_time
-
-    override_current_time(s, s.next_time)
-    s.step
-    assert_equal 2, s.steps
     assert_equal (s.current_time + 2), s.next_time
 
     override_current_time(s, s.next_time)
     s.step
-    assert_equal 3, s.steps
+    assert_equal 2, s.steps
     assert_equal (s.current_time + 4), s.next_time
 
     assert !s.limit?
 
-    # + 8 (=16) > 12
+    # + 8 (=15) > 12
 
     override_current_time(s, s.next_time)
     s.step
-    assert_equal 4, s.steps
+    assert_equal 3, s.steps
     assert_equal s.timeout_at, s.next_time
 
+    s.step
     assert s.limit?
   end
 
@@ -293,24 +306,24 @@ class Dummy < Fluent::Plugin::TestBase
     override_current_time(s, s.next_time)
     s.step
     assert_equal 1, s.steps
-    assert_equal (s.current_time + 1), s.next_time
+    assert_equal (s.current_time + 2), s.next_time
 
     override_current_time(s, s.next_time)
     s.step
     assert_equal 2, s.steps
-    assert_equal (s.current_time + 2), s.next_time
+    assert_equal (s.current_time + 4), s.next_time
 
     override_current_time(s, s.next_time)
     s.step
     assert_equal 3, s.steps
-    assert_equal (s.current_time + 4), s.next_time
+    assert_equal (s.current_time + 8), s.next_time
 
     assert !s.limit?
 
     override_current_time(s, s.next_time)
     s.step
     assert_equal 4, s.steps
-    assert_equal (s.current_time + 8), s.next_time
+    assert_equal (s.current_time + 10), s.next_time
 
     assert !s.limit?
 
@@ -324,8 +337,6 @@ class Dummy < Fluent::Plugin::TestBase
     override_current_time(s, s.next_time)
     s.step
     assert_equal 6, s.steps
-    assert_equal (s.current_time + 10), s.next_time
-
     assert s.limit?
   end
 
@@ -341,40 +352,42 @@ class Dummy < Fluent::Plugin::TestBase
     assert_equal (dummy_current_time + 1), s.next_time
     assert !s.secondary?
 
-    # 1, 1(2), 2(4), 4(8), 8(16), 16(32), 32(64), (80), (81), (83), (87), (95), (100)
+    # primary: 3, 7, 15, 31, 63, 80 (timeout * threashold)
+    # secondary: 81, 83, 87, 95, 100
     i = 1
-    while i < 7
+    while i < 6
       override_current_time(s, s.next_time)
       assert !s.secondary?
 
       s.step
       assert_equal i, s.steps
-      assert_equal (s.current_time + 1 * (2 ** (i - 1))), s.next_time
+      assert_equal (s.current_time + 1 * (2 ** i)), s.next_time
       assert !s.limit?
       i += 1
     end
 
-    assert_equal 7, i
-    override_current_time(s, s.next_time) # 64
+    assert_equal 6, i
+    override_current_time(s, s.next_time) # 63
     assert !s.secondary?
 
     s.step
-    assert_equal 7, s.steps
+    assert_equal 6, s.steps
     assert_equal s.secondary_transition_at, s.next_time
     assert !s.limit?
 
     i += 1
-    assert_equal 8, i
+    assert_equal 7, i
     override_current_time(s, s.next_time) # 80
     assert s.secondary?
 
     s.step
-    assert_equal 8, s.steps
+    assert_equal 7, s.steps
     assert_equal s.steps, s.secondary_transition_steps
-    assert_equal (s.secondary_transition_at + 1.0), s.next_time
+    assert_equal (s.secondary_transition_at + 1.0), s.next_time # 81
     assert !s.limit?
+    assert_equal :secondary, s.current
 
-    # 81, 82, 84, 88, 96, 100
+    # 83, 87, 95, 100
     j = 1
     while j < 4
       override_current_time(s, s.next_time)
@@ -382,18 +395,20 @@ class Dummy < Fluent::Plugin::TestBase
       assert_equal :secondary, s.current
 
       s.step
-      assert_equal (8 + j), s.steps
+      assert_equal (7 + j), s.steps
       assert_equal (s.current_time + (1 * (2 ** j))), s.next_time
       assert !s.limit?, "j:#{j}"
       j += 1
     end
 
     assert_equal 4, j
-    override_current_time(s, s.next_time) # 96
+    override_current_time(s, s.next_time) # 95
     assert s.secondary?
 
     s.step
-    assert_equal s.timeout_at, s.next_time
+    assert_equal s.timeout_at, s.next_time # 100
+
+    s.step
     assert s.limit?
   end
 
@@ -439,4 +454,553 @@ class Dummy < Fluent::Plugin::TestBase
       end
     end
   end
+
+  sub_test_case "ExponentialBackOff_ScenarioTests" do
+    data("Simple timeout", {
+      timeout: 100, max_steps: nil, max_interval: nil, use_sec: false, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 100, false),
+      ],
+    })
+    data("Simple timeout with secondary", {
+      timeout: 100, max_steps: nil, max_interval: nil, use_sec: true, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 80, true),
+        RetryRecord.new(8, 81, true),
+        RetryRecord.new(9, 83, true),
+        RetryRecord.new(10, 87, true),
+        RetryRecord.new(11, 95, true),
+        RetryRecord.new(12, 100, true),
+      ],
+    })
+    data("Simple timeout with custom wait and backoff_base", {
+      timeout: 1000, max_steps: nil, max_interval: nil, use_sec: false, sec_thres: 0.8, wait: 2, backoff_base: 3,
+      expected: [
+        RetryRecord.new(1, 2, false),
+        RetryRecord.new(2, 8, false),
+        RetryRecord.new(3, 26, false),
+        RetryRecord.new(4, 80, false),
+        RetryRecord.new(5, 242, false),
+        RetryRecord.new(6, 728, false),
+        RetryRecord.new(7, 1000, false),
+      ],
+    })
+    data("Simple timeout with custom wait and backoff_base and secondary", {
+      timeout: 1000, max_steps: nil, max_interval: nil, use_sec: true, sec_thres: 0.8, wait: 2, backoff_base: 3,
+      expected: [
+        RetryRecord.new(1, 2, false),
+        RetryRecord.new(2, 8, false),
+        RetryRecord.new(3, 26, false),
+        RetryRecord.new(4, 80, false),
+        RetryRecord.new(5, 242, false),
+        RetryRecord.new(6, 728, false),
+        RetryRecord.new(7, 800, true),
+        RetryRecord.new(8, 802, true),
+        RetryRecord.new(9, 808, true),
+        RetryRecord.new(10, 826, true),
+        RetryRecord.new(11, 880, true),
+        RetryRecord.new(12, 1000, true),
+      ],
+    })
+    data("Default timeout", {
+      timeout: 72*3600, max_steps: nil, max_interval: nil, use_sec: false, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 8191, false),
+        RetryRecord.new(14, 16383, false),
+        RetryRecord.new(15, 32767, false),
+        RetryRecord.new(16, 65535, false),
+        RetryRecord.new(17, 131071, false),
+        RetryRecord.new(18, 259200, false),
+      ],
+    })
+    data("Default timeout with secondary", {
+      timeout: 72*3600, max_steps: nil, max_interval: nil, use_sec: true, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 8191, false),
+        RetryRecord.new(14, 16383, false),
+        RetryRecord.new(15, 32767, false),
+        RetryRecord.new(16, 65535, false),
+        RetryRecord.new(17, 131071, false),
+        RetryRecord.new(18, 207360, true),
+        RetryRecord.new(19, 207361, true),
+        RetryRecord.new(20, 207363, true),
+        RetryRecord.new(21, 207367, true),
+        RetryRecord.new(22, 207375, true),
+        RetryRecord.new(23, 207391, true),
+        RetryRecord.new(24, 207423, true),
+        RetryRecord.new(25, 207487, true),
+        RetryRecord.new(26, 207615, true),
+        RetryRecord.new(27, 207871, true),
+        RetryRecord.new(28, 208383, true),
+        RetryRecord.new(29, 209407, true),
+        RetryRecord.new(30, 211455, true),
+        RetryRecord.new(31, 215551, true),
+        RetryRecord.new(32, 223743, true),
+        RetryRecord.new(33, 240127, true),
+        RetryRecord.new(34, 259200, true),
+      ],
+    })
+    data("Default timeout with secondary and custom threshold", {
+      timeout: 72*3600, max_steps: nil, max_interval: nil, use_sec: true, sec_thres: 0.5, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 8191, false),
+        RetryRecord.new(14, 16383, false),
+        RetryRecord.new(15, 32767, false),
+        RetryRecord.new(16, 65535, false),
+        RetryRecord.new(17, 129600, true),
+        RetryRecord.new(18, 129601, true),
+        RetryRecord.new(19, 129603, true),
+        RetryRecord.new(20, 129607, true),
+        RetryRecord.new(21, 129615, true),
+        RetryRecord.new(22, 129631, true),
+        RetryRecord.new(23, 129663, true),
+        RetryRecord.new(24, 129727, true),
+        RetryRecord.new(25, 129855, true),
+        RetryRecord.new(26, 130111, true),
+        RetryRecord.new(27, 130623, true),
+        RetryRecord.new(28, 131647, true),
+        RetryRecord.new(29, 133695, true),
+        RetryRecord.new(30, 137791, true),
+        RetryRecord.new(31, 145983, true),
+        RetryRecord.new(32, 162367, true),
+        RetryRecord.new(33, 195135, true),
+        RetryRecord.new(34, 259200, true),
+      ],
+    })
+    data("Simple max_steps", {
+      timeout: 72*3600, max_steps: 10, max_interval: nil, use_sec: false, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+      ],
+    })
+    data("Simple max_steps with secondary", {
+      timeout: 72*3600, max_steps: 10, max_interval: nil, use_sec: true, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 818, true),
+      ],
+    })
+    data("Simple interval", {
+      timeout: 72*3600, max_steps: nil, max_interval: 3600, use_sec: false, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 7695, false),
+        RetryRecord.new(14, 11295, false),
+        RetryRecord.new(15, 14895, false),
+        RetryRecord.new(16, 18495, false),
+        RetryRecord.new(17, 22095, false),
+        RetryRecord.new(18, 25695, false),
+        RetryRecord.new(19, 29295, false),
+        RetryRecord.new(20, 32895, false),
+        RetryRecord.new(21, 36495, false),
+        RetryRecord.new(22, 40095, false),
+        RetryRecord.new(23, 43695, false),
+        RetryRecord.new(24, 47295, false),
+        RetryRecord.new(25, 50895, false),
+        RetryRecord.new(26, 54495, false),
+        RetryRecord.new(27, 58095, false),
+        RetryRecord.new(28, 61695, false),
+        RetryRecord.new(29, 65295, false),
+        RetryRecord.new(30, 68895, false),
+        RetryRecord.new(31, 72495, false),
+        RetryRecord.new(32, 76095, false),
+        RetryRecord.new(33, 79695, false),
+        RetryRecord.new(34, 83295, false),
+        RetryRecord.new(35, 86895, false),
+        RetryRecord.new(36, 90495, false),
+        RetryRecord.new(37, 94095, false),
+        RetryRecord.new(38, 97695, false),
+        RetryRecord.new(39, 101295, false),
+        RetryRecord.new(40, 104895, false),
+        RetryRecord.new(41, 108495, false),
+        RetryRecord.new(42, 112095, false),
+        RetryRecord.new(43, 115695, false),
+        RetryRecord.new(44, 119295, false),
+        RetryRecord.new(45, 122895, false),
+        RetryRecord.new(46, 126495, false),
+        RetryRecord.new(47, 130095, false),
+        RetryRecord.new(48, 133695, false),
+        RetryRecord.new(49, 137295, false),
+        RetryRecord.new(50, 140895, false),
+        RetryRecord.new(51, 144495, false),
+        RetryRecord.new(52, 148095, false),
+        RetryRecord.new(53, 151695, false),
+        RetryRecord.new(54, 155295, false),
+        RetryRecord.new(55, 158895, false),
+        RetryRecord.new(56, 162495, false),
+        RetryRecord.new(57, 166095, false),
+        RetryRecord.new(58, 169695, false),
+        RetryRecord.new(59, 173295, false),
+        RetryRecord.new(60, 176895, false),
+        RetryRecord.new(61, 180495, false),
+        RetryRecord.new(62, 184095, false),
+        RetryRecord.new(63, 187695, false),
+        RetryRecord.new(64, 191295, false),
+        RetryRecord.new(65, 194895, false),
+        RetryRecord.new(66, 198495, false),
+        RetryRecord.new(67, 202095, false),
+        RetryRecord.new(68, 205695, false),
+        RetryRecord.new(69, 209295, false),
+        RetryRecord.new(70, 212895, false),
+        RetryRecord.new(71, 216495, false),
+        RetryRecord.new(72, 220095, false),
+        RetryRecord.new(73, 223695, false),
+        RetryRecord.new(74, 227295, false),
+        RetryRecord.new(75, 230895, false),
+        RetryRecord.new(76, 234495, false),
+        RetryRecord.new(77, 238095, false),
+        RetryRecord.new(78, 241695, false),
+        RetryRecord.new(79, 245295, false),
+        RetryRecord.new(80, 248895, false),
+        RetryRecord.new(81, 252495, false),
+        RetryRecord.new(82, 256095, false),
+        RetryRecord.new(83, 259200, false),
+      ],
+    })
+    data("Simple interval with secondary", {
+      timeout: 72*3600, max_steps: nil, max_interval: 3600, use_sec: true, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 7695, false),
+        RetryRecord.new(14, 11295, false),
+        RetryRecord.new(15, 14895, false),
+        RetryRecord.new(16, 18495, false),
+        RetryRecord.new(17, 22095, false),
+        RetryRecord.new(18, 25695, false),
+        RetryRecord.new(19, 29295, false),
+        RetryRecord.new(20, 32895, false),
+        RetryRecord.new(21, 36495, false),
+        RetryRecord.new(22, 40095, false),
+        RetryRecord.new(23, 43695, false),
+        RetryRecord.new(24, 47295, false),
+        RetryRecord.new(25, 50895, false),
+        RetryRecord.new(26, 54495, false),
+        RetryRecord.new(27, 58095, false),
+        RetryRecord.new(28, 61695, false),
+        RetryRecord.new(29, 65295, false),
+        RetryRecord.new(30, 68895, false),
+        RetryRecord.new(31, 72495, false),
+        RetryRecord.new(32, 76095, false),
+        RetryRecord.new(33, 79695, false),
+        RetryRecord.new(34, 83295, false),
+        RetryRecord.new(35, 86895, false),
+        RetryRecord.new(36, 90495, false),
+        RetryRecord.new(37, 94095, false),
+        RetryRecord.new(38, 97695, false),
+        RetryRecord.new(39, 101295, false),
+        RetryRecord.new(40, 104895, false),
+        RetryRecord.new(41, 108495, false),
+        RetryRecord.new(42, 112095, false),
+        RetryRecord.new(43, 115695, false),
+        RetryRecord.new(44, 119295, false),
+        RetryRecord.new(45, 122895, false),
+        RetryRecord.new(46, 126495, false),
+        RetryRecord.new(47, 130095, false),
+        RetryRecord.new(48, 133695, false),
+        RetryRecord.new(49, 137295, false),
+        RetryRecord.new(50, 140895, false),
+        RetryRecord.new(51, 144495, false),
+        RetryRecord.new(52, 148095, false),
+        RetryRecord.new(53, 151695, false),
+        RetryRecord.new(54, 155295, false),
+        RetryRecord.new(55, 158895, false),
+        RetryRecord.new(56, 162495, false),
+        RetryRecord.new(57, 166095, false),
+        RetryRecord.new(58, 169695, false),
+        RetryRecord.new(59, 173295, false),
+        RetryRecord.new(60, 176895, false),
+        RetryRecord.new(61, 180495, false),
+        RetryRecord.new(62, 184095, false),
+        RetryRecord.new(63, 187695, false),
+        RetryRecord.new(64, 191295, false),
+        RetryRecord.new(65, 194895, false),
+        RetryRecord.new(66, 198495, false),
+        RetryRecord.new(67, 202095, false),
+        RetryRecord.new(68, 205695, false),
+        RetryRecord.new(69, 207360, true),
+        RetryRecord.new(70, 207361, true),
+        RetryRecord.new(71, 207363, true),
+        RetryRecord.new(72, 207367, true),
+        RetryRecord.new(73, 207375, true),
+        RetryRecord.new(74, 207391, true),
+        RetryRecord.new(75, 207423, true),
+        RetryRecord.new(76, 207487, true),
+        RetryRecord.new(77, 207615, true),
+        RetryRecord.new(78, 207871, true),
+        RetryRecord.new(79, 208383, true),
+        RetryRecord.new(80, 209407, true),
+        RetryRecord.new(81, 211455, true),
+        RetryRecord.new(82, 215055, true),
+        RetryRecord.new(83, 218655, true),
+        RetryRecord.new(84, 222255, true),
+        RetryRecord.new(85, 225855, true),
+        RetryRecord.new(86, 229455, true),
+        RetryRecord.new(87, 233055, true),
+        RetryRecord.new(88, 236655, true),
+        RetryRecord.new(89, 240255, true),
+        RetryRecord.new(90, 243855, true),
+        RetryRecord.new(91, 247455, true),
+        RetryRecord.new(92, 251055, true),
+        RetryRecord.new(93, 254655, true),
+        RetryRecord.new(94, 258255, true),
+        RetryRecord.new(95, 259200, true),
+      ],
+    })
+    data("Max_steps and max_interval", {
+      timeout: 72*3600, max_steps: 30, max_interval: 3600, use_sec: false, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 7695, false),
+        RetryRecord.new(14, 11295, false),
+        RetryRecord.new(15, 14895, false),
+        RetryRecord.new(16, 18495, false),
+        RetryRecord.new(17, 22095, false),
+        RetryRecord.new(18, 25695, false),
+        RetryRecord.new(19, 29295, false),
+        RetryRecord.new(20, 32895, false),
+        RetryRecord.new(21, 36495, false),
+        RetryRecord.new(22, 40095, false),
+        RetryRecord.new(23, 43695, false),
+        RetryRecord.new(24, 47295, false),
+        RetryRecord.new(25, 50895, false),
+        RetryRecord.new(26, 54495, false),
+        RetryRecord.new(27, 58095, false),
+        RetryRecord.new(28, 61695, false),
+        RetryRecord.new(29, 65295, false),
+        RetryRecord.new(30, 68895, false),
+      ],
+    })
+    data("Max_steps and max_interval with secondary", {
+      timeout: 72*3600, max_steps: 30, max_interval: 3600, use_sec: true, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2047, false),
+        RetryRecord.new(12, 4095, false),
+        RetryRecord.new(13, 7695, false),
+        RetryRecord.new(14, 11295, false),
+        RetryRecord.new(15, 14895, false),
+        RetryRecord.new(16, 18495, false),
+        RetryRecord.new(17, 22095, false),
+        RetryRecord.new(18, 25695, false),
+        RetryRecord.new(19, 29295, false),
+        RetryRecord.new(20, 32895, false),
+        RetryRecord.new(21, 36495, false),
+        RetryRecord.new(22, 40095, false),
+        RetryRecord.new(23, 43695, false),
+        RetryRecord.new(24, 47295, false),
+        RetryRecord.new(25, 50895, false),
+        RetryRecord.new(26, 54495, false),
+        RetryRecord.new(27, 55116, true),
+        RetryRecord.new(28, 55117, true),
+        RetryRecord.new(29, 55119, true),
+        RetryRecord.new(30, 55123, true),
+      ],
+    })
+    data("Max_steps and max_interval with timeout", {
+      timeout: 10000, max_steps: 30, max_interval: 1000, use_sec: false, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2023, false),
+        RetryRecord.new(12, 3023, false),
+        RetryRecord.new(13, 4023, false),
+        RetryRecord.new(14, 5023, false),
+        RetryRecord.new(15, 6023, false),
+        RetryRecord.new(16, 7023, false),
+        RetryRecord.new(17, 8023, false),
+        RetryRecord.new(18, 9023, false),
+        RetryRecord.new(19, 10000, false),
+      ],
+    })
+    data("Max_steps and max_interval with timeout and secondary", {
+      timeout: 10000, max_steps: 30, max_interval: 1000, use_sec: true, sec_thres: 0.8, wait: 1, backoff_base: 2,
+      expected: [
+        RetryRecord.new(1, 1, false),
+        RetryRecord.new(2, 3, false),
+        RetryRecord.new(3, 7, false),
+        RetryRecord.new(4, 15, false),
+        RetryRecord.new(5, 31, false),
+        RetryRecord.new(6, 63, false),
+        RetryRecord.new(7, 127, false),
+        RetryRecord.new(8, 255, false),
+        RetryRecord.new(9, 511, false),
+        RetryRecord.new(10, 1023, false),
+        RetryRecord.new(11, 2023, false),
+        RetryRecord.new(12, 3023, false),
+        RetryRecord.new(13, 4023, false),
+        RetryRecord.new(14, 5023, false),
+        RetryRecord.new(15, 6023, false),
+        RetryRecord.new(16, 7023, false),
+        RetryRecord.new(17, 8000, true),
+        RetryRecord.new(18, 8001, true),
+        RetryRecord.new(19, 8003, true),
+        RetryRecord.new(20, 8007, true),
+        RetryRecord.new(21, 8015, true),
+        RetryRecord.new(22, 8031, true),
+        RetryRecord.new(23, 8063, true),
+        RetryRecord.new(24, 8127, true),
+        RetryRecord.new(25, 8255, true),
+        RetryRecord.new(26, 8511, true),
+        RetryRecord.new(27, 9023, true),
+        RetryRecord.new(28, 10000, true),
+      ],
+    })
+    test "exponential backoff with senario" do |data|
+      print_for_debug = false # change this value true if need to see msg always.
+      trying_count = 1000 # just for avoiding infinite loop
+
+      retry_records = []
+      msg = ""
+
+      s = @d.retry_state_create(
+        :t15, :exponential_backoff, data[:wait], data[:timeout],
+        max_steps: data[:max_steps], max_interval: data[:max_interval],
+        secondary: data[:use_sec], secondary_threshold: data[:sec_thres],
+        backoff_base: data[:backoff_base], randomize: false
+      )
+      override_current_time(s, s.start)
+
+      retry_count = 0
+      trying_count.times do
+        next_elapsed = (s.next_time - s.start).to_i
+
+        msg << "step: #{s.steps}, next: #{next_elapsed}s (#{next_elapsed / 3600}h)\n"
+
+        # Wait until next time to trigger the next retry
+        override_current_time(s, s.next_time)
+
+        # Retry will be triggered at this point.
+        retry_count += 1
+        rec = RetryRecord.new(retry_count, next_elapsed, s.secondary?)
+        retry_records.append(rec)
+        msg << "[#{next_elapsed}s elapsed point] #{retry_count}th-Retry(#{s.secondary? ? "SEC" : "PRI"}) is triggered.\n"
+
+        # Update retry statement
+        s.step
+        if s.limit?
+          msg << "--- Reach limit. ---\n"
+          break
+        end
+      end
+
+      assert_equal(data[:expected], retry_records, msg)
+
+      print(msg) if print_for_debug
+    end
+  end
 end