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in_tail: Manage tail watchers that are rorate_wait state too (#4334)
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After a tail watcher transitions to `rotate_wait` state, the
`rotate_wait` timer is no longer managed by in_tail, it might cause
unexpected behaviour. e.g.)

* It's never unwatched when shutdown occurs before `rotate_wait` passed.
* Needless `rotate_wait` timers are executed when it detects more
  rotations.

This patch fixes such unexpected behaviour.

Note: The comment about `detach_watcher` was added in 76f246a.
At that time, closing was done by event-loop.
Now, the situation is completely different, so it should be removed.

---------

Signed-off-by: Takuro Ashie <[email protected]>
Co-authored-by: Daijiro Fukuda <[email protected]>
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@ashie @daipom
ashie and daipom authored Mar 8, 2024
1 parent c56f91e commit 83273e0
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Showing 2 changed files with 184 additions and 9 deletions.
24 changes: 18 additions & 6 deletions lib/fluent/plugin/in_tail.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@ def initialize
super
@paths = []
@tails = {}
@tails_rotate_wait = {}
@pf_file = nil
@pf = nil
@ignore_list = []
Expand Down Expand Up @@ -267,6 +268,9 @@ def shutdown
@shutdown_start_time = Fluent::Clock.now
# during shutdown phase, don't close io. It should be done in close after all threads are stopped. See close.
stop_watchers(existence_path, immediate: true, remove_watcher: false)
@tails_rotate_wait.keys.each do |tw|
detach_watcher(tw, @tails_rotate_wait[tw][:ino], false)
end
@pf_file.close if @pf_file

super
Expand All @@ -275,6 +279,7 @@ def shutdown
def close
super
# close file handles after all threads stopped (in #close of thread plugin helper)
# It may be because we need to wait IOHanlder.ready_to_shutdown()
close_watcher_handles
end

Expand Down Expand Up @@ -516,6 +521,9 @@ def close_watcher_handles
tw.close
end
end
@tails_rotate_wait.keys.each do |tw|
tw.close
end
end

# refresh_watchers calls @tails.keys so we don't use stop_watcher -> start_watcher sequence for safety.
Expand Down Expand Up @@ -570,10 +578,6 @@ def update_watcher(tail_watcher, pe, new_inode)
detach_watcher_after_rotate_wait(tail_watcher, pe.read_inode)
end

# TailWatcher#close is called by another thread at shutdown phase.
# It causes 'can't modify string; temporarily locked' error in IOHandler
# so adding close_io argument to avoid this problem.
# At shutdown, IOHandler's io will be released automatically after detached the event loop
def detach_watcher(tw, ino, close_io = true)
if @follow_inodes && tw.ino != ino
log.warn("detach_watcher could be detaching an unexpected tail_watcher with a different ino.",
Expand Down Expand Up @@ -604,22 +608,30 @@ def detach_watcher_after_rotate_wait(tw, ino)
if @open_on_every_update
# Detach now because it's already closed, waiting it doesn't make sense.
detach_watcher(tw, ino)
elsif throttling_is_enabled?(tw)
end

return if @tails_rotate_wait[tw]

if throttling_is_enabled?(tw)
# When the throttling feature is enabled, it might not reach EOF yet.
# Should ensure to read all contents before closing it, with keeping throttling.
start_time_to_wait = Fluent::Clock.now
timer = timer_execute(:in_tail_close_watcher, 1, repeat: true) do
elapsed = Fluent::Clock.now - start_time_to_wait
if tw.eof? && elapsed >= @rotate_wait
timer.detach
@tails_rotate_wait.delete(tw)
detach_watcher(tw, ino)
end
end
@tails_rotate_wait[tw] = { ino: ino, timer: timer }
else
# when the throttling feature isn't enabled, just wait @rotate_wait
timer_execute(:in_tail_close_watcher, @rotate_wait, repeat: false) do
timer = timer_execute(:in_tail_close_watcher, @rotate_wait, repeat: false) do
@tails_rotate_wait.delete(tw)
detach_watcher(tw, ino)
end
@tails_rotate_wait[tw] = { ino: ino, timer: timer }
end
end

Expand Down
169 changes: 166 additions & 3 deletions test/plugin/test_in_tail.rb
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3016,6 +3016,92 @@ def test_path_resurrection
},
)
end

def test_next_rotation_occurs_very_fast_while_old_TW_still_waiting_rotate_wait
config = config_element(
"ROOT",
"",
{
"path" => "#{@tmp_dir}/tail.txt*",
"pos_file" => "#{@tmp_dir}/tail.pos",
"tag" => "t1",
"format" => "none",
"read_from_head" => "true",
"follow_inodes" => "true",
"rotate_wait" => "3s",
"refresh_interval" => "1h",
# stat_watcher often calls `TailWatcher::on_notify` faster than creating a new log file,
# so disable it in order to reproduce the same condition stably.
"enable_stat_watcher" => "false",
}
)
d = create_driver(config, false)

tail_watchers = []
stub.proxy(d.instance).setup_watcher do |tw|
tail_watchers.append(tw)
mock.proxy(tw).close.once # Note: Currently, there is no harm in duplicate calls.
tw
end

Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "wb") {|f| f.puts "file1 log1"}

d.run(expect_records: 6, timeout: 15) do
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file1 log2"}

sleep 1.5 # Need to be larger than 1s (the interval of watch_timer)

FileUtils.move("#{@tmp_dir}/tail.txt0", "#{@tmp_dir}/tail.txt" + "1")
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "wb") {|f| f.puts "file2 log1"}
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file2 log2"}

sleep 1.5 # Need to be larger than 1s (the interval of watch_timer)

# Rotate again (Old TailWatcher waiting rotate_wait also calls update_watcher)
[1, 0].each do |i|
FileUtils.move("#{@tmp_dir}/tail.txt#{i}", "#{@tmp_dir}/tail.txt#{i + 1}")
end
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "wb") {|f| f.puts "file3 log1"}
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file3 log2"}

# Wait rotate_wait to confirm that TailWatcher.close is not called in duplicate.
# (Note: Currently, there is no harm in duplicate calls)
sleep 4
end

inode_0 = tail_watchers[0]&.ino
inode_1 = tail_watchers[1]&.ino
inode_2 = tail_watchers[2]&.ino
record_values = d.events.collect { |event| event[2]["message"] }.sort
position_entries = []
Fluent::FileWrapper.open("#{@tmp_dir}/tail.pos", "r") do |f|
f.readlines(chomp: true).each do |line|
values = line.split("\t")
position_entries.append([values[0], values[1], values[2].to_i(16)])
end
end

assert_equal(
{
record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2", "file3 log1", "file3 log2"],
tail_watcher_paths: ["#{@tmp_dir}/tail.txt0", "#{@tmp_dir}/tail.txt0", "#{@tmp_dir}/tail.txt0"],
tail_watcher_inodes: [inode_0, inode_1, inode_2],
tail_watcher_io_handler_opened_statuses: [false, false, false],
position_entries: [
["#{@tmp_dir}/tail.txt0", "0000000000000016", inode_0],
["#{@tmp_dir}/tail.txt0", "0000000000000016", inode_1],
["#{@tmp_dir}/tail.txt0", "0000000000000016", inode_2],
],
},
{
record_values: record_values,
tail_watcher_paths: tail_watchers.collect { |tw| tw.path },
tail_watcher_inodes: tail_watchers.collect { |tw| tw.ino },
tail_watcher_io_handler_opened_statuses: tail_watchers.collect { |tw| tw.instance_variable_get(:@io_handler)&.opened? || false },
position_entries: position_entries
},
)
end
end

sub_test_case "Update watchers for rotation without follow_inodes" do
Expand Down Expand Up @@ -3084,9 +3170,6 @@ def test_refreshTW_during_rotation
sleep 3

Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file3 log2"}

# Wait `rotate_wait` for file2 to make sure to close all IO handlers
sleep 3
end

inode_0 = tail_watchers[0]&.ino
Expand Down Expand Up @@ -3121,5 +3204,85 @@ def test_refreshTW_during_rotation
},
)
end

def test_next_rotation_occurs_very_fast_while_old_TW_still_waiting_rotate_wait
config = config_element(
"ROOT",
"",
{
"path" => "#{@tmp_dir}/tail.txt0",
"pos_file" => "#{@tmp_dir}/tail.pos",
"tag" => "t1",
"format" => "none",
"read_from_head" => "true",
"rotate_wait" => "3s",
"refresh_interval" => "1h",
}
)
d = create_driver(config, false)

tail_watchers = []
stub.proxy(d.instance).setup_watcher do |tw|
tail_watchers.append(tw)
mock.proxy(tw).close.once # Note: Currently, there is no harm in duplicate calls.
tw
end

Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "wb") {|f| f.puts "file1 log1"}

d.run(expect_records: 6, timeout: 15) do
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file1 log2"}

sleep 1.5 # Need to be larger than 1s (the interval of watch_timer)

FileUtils.move("#{@tmp_dir}/tail.txt0", "#{@tmp_dir}/tail.txt" + "1")
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "wb") {|f| f.puts "file2 log1"}
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file2 log2"}

sleep 1.5 # Need to be larger than 1s (the interval of watch_timer)

# Rotate again (Old TailWatcher waiting rotate_wait also calls update_watcher)
[1, 0].each do |i|
FileUtils.move("#{@tmp_dir}/tail.txt#{i}", "#{@tmp_dir}/tail.txt#{i + 1}")
end
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "wb") {|f| f.puts "file3 log1"}
Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt0", "ab") {|f| f.puts "file3 log2"}

# Wait rotate_wait to confirm that TailWatcher.close is not called in duplicate.
# (Note: Currently, there is no harm in duplicate calls)
sleep 4
end

inode_0 = tail_watchers[0]&.ino
inode_1 = tail_watchers[1]&.ino
inode_2 = tail_watchers[2]&.ino
record_values = d.events.collect { |event| event[2]["message"] }.sort
position_entries = []
Fluent::FileWrapper.open("#{@tmp_dir}/tail.pos", "r") do |f|
f.readlines(chomp: true).each do |line|
values = line.split("\t")
position_entries.append([values[0], values[1], values[2].to_i(16)])
end
end

assert_equal(
{
record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2", "file3 log1", "file3 log2"],
tail_watcher_paths: ["#{@tmp_dir}/tail.txt0", "#{@tmp_dir}/tail.txt0", "#{@tmp_dir}/tail.txt0"],
tail_watcher_inodes: [inode_0, inode_1, inode_2],
tail_watcher_io_handler_opened_statuses: [false, false, false],
position_entries: [
["#{@tmp_dir}/tail.txt0", "0000000000000016", inode_2],
],
},
{
record_values: record_values,
tail_watcher_paths: tail_watchers.collect { |tw| tw.path },
tail_watcher_inodes: tail_watchers.collect { |tw| tw.ino },
tail_watcher_io_handler_opened_statuses: tail_watchers.collect { |tw| tw.instance_variable_get(:@io_handler)&.opened? || false },
position_entries: position_entries
},
)
end
end
end

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