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HADOOP-18546. ABFS:disable purging list of in progress reads in abfs stream closed #5176

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Merged
steveloughran merged 16 commits into from
Dec 7, 2022
Merged

HADOOP-18546. ABFS:disable purging list of in progress reads in abfs stream closed #5176

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54e706a
InProgressList not to be purged on the stream close.
saxenapranav Dec 1, 2022
39c3403
added test. concurrency issues
saxenapranav Dec 1, 2022
8cad3d5
fixed consistency issue in the testAbfsInputStream new tests
saxenapranav Dec 1, 2022
a8eb44b
improved javadocs
saxenapranav Dec 1, 2022
11ff043
Merge branch 'trunk' into HADOOP-18546
saxenapranav Dec 1, 2022
ddefd2e
added wait after test run to delete any completed buffers
saxenapranav Dec 1, 2022
6a1e0a6
test simplified.
saxenapranav Dec 1, 2022
02d39ca
Revert "HADOOP-18528. Disable abfs prefetching by default (#5134)"
saxenapranav Dec 1, 2022
2a6dcb6
true value for fs.azure.enable.readahead in core-default.xml; basic A…
saxenapranav Dec 2, 2022
fc833f2
refactored testStreamPurgeDuringReadAheadCallExecuting to remove depe…
saxenapranav Dec 2, 2022
11dd7bf
Revert "refactored testStreamPurgeDuringReadAheadCallExecuting to rem…
saxenapranav Dec 2, 2022
ac1e758
removal of assertion for inprogress to completedList and eviction whi…
saxenapranav Dec 2, 2022
64546a5
javadoc for test: refactor
saxenapranav Dec 2, 2022
4902598
checkstyle:magicNumber fix
saxenapranav Dec 5, 2022
c76f610
try-with-resources block for abfsInputStream in test; usage of String…
saxenapranav Dec 7, 2022
455a472
Merge branch 'trunk' into HADOOP-18546
saxenapranav Dec 7, 2022
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5 changes: 2 additions & 3 deletions hadoop-common-project/hadoop-common/src/main/resources/core-default.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -2168,9 +2168,8 @@ The switch to turn S3A auditing on or off.

<property>
<name>fs.azure.enable.readahead</name>
<value>false</value>
<description>Disable readahead/prefetching in AbfsInputStream.
See HADOOP-18521</description>
<value>true</value>
<description>Enabled readahead/prefetching in AbfsInputStream.</description>
</property>

<property>
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2 changes: 1 addition & 1 deletion ...azure/src/main/java/org/apache/hadoop/fs/azurebfs/constants/FileSystemConfigurations.java
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Expand Up @@ -109,7 +109,7 @@ public final class FileSystemConfigurations {
public static final boolean DEFAULT_ABFS_LATENCY_TRACK = false;
public static final long DEFAULT_SAS_TOKEN_RENEW_PERIOD_FOR_STREAMS_IN_SECONDS = 120;

public static final boolean DEFAULT_ENABLE_READAHEAD = false;
public static final boolean DEFAULT_ENABLE_READAHEAD = true;
public static final String DEFAULT_FS_AZURE_USER_AGENT_PREFIX = EMPTY_STRING;
public static final String DEFAULT_VALUE_UNKNOWN = "UNKNOWN";

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2 changes: 1 addition & 1 deletion ...op-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsInputStreamContext.java
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Expand Up @@ -35,7 +35,7 @@ public class AbfsInputStreamContext extends AbfsStreamContext {

private boolean tolerateOobAppends;

private boolean isReadAheadEnabled = false;
private boolean isReadAheadEnabled = true;

private boolean alwaysReadBufferSize;

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6 changes: 5 additions & 1 deletion .../hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/ReadBufferManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -544,7 +544,6 @@ public synchronized void purgeBuffersForStream(AbfsInputStream stream) {
LOGGER.debug("Purging stale buffers for AbfsInputStream {} ", stream);
readAheadQueue.removeIf(readBuffer -> readBuffer.getStream() == stream);
purgeList(stream, completedReadList);
purgeList(stream, inProgressList);
}

/**
Expand Down Expand Up @@ -642,4 +641,9 @@ void testMimicFullUseAndAddFailedBuffer(ReadBuffer buf) {
freeList.clear();
completedReadList.add(buf);
}

@VisibleForTesting
int getNumBuffers() {
return NUM_BUFFERS;
}
}
2 changes: 0 additions & 2 deletions ...src/test/java/org/apache/hadoop/fs/azurebfs/contract/ITestAbfsFileSystemContractSeek.java
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Expand Up @@ -34,7 +34,6 @@

import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.AZURE_READ_AHEAD_RANGE;
import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.AZURE_READ_BUFFER_SIZE;
import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.FS_AZURE_ENABLE_READAHEAD;
import static org.apache.hadoop.fs.azurebfs.constants.FileSystemConfigurations.MIN_BUFFER_SIZE;
import static org.apache.hadoop.fs.contract.ContractTestUtils.createFile;
import static org.apache.hadoop.fs.contract.ContractTestUtils.dataset;
Expand Down Expand Up @@ -69,7 +68,6 @@ protected Configuration createConfiguration() {
protected AbstractFSContract createContract(final Configuration conf) {
conf.setInt(AZURE_READ_AHEAD_RANGE, MIN_BUFFER_SIZE);
conf.setInt(AZURE_READ_BUFFER_SIZE, MIN_BUFFER_SIZE);
conf.setBoolean(FS_AZURE_ENABLE_READAHEAD, true);
return new AbfsFileSystemContract(conf, isSecure);
}

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65 changes: 63 additions & 2 deletions ...adoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/services/TestAbfsInputStream.java
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Expand Up @@ -82,6 +82,12 @@ public class TestAbfsInputStream extends
REDUCED_READ_BUFFER_AGE_THRESHOLD * 10; // 30 sec
private static final int ALWAYS_READ_BUFFER_SIZE_TEST_FILE_SIZE = 16 * ONE_MB;

@Override
public void teardown() throws Exception {
super.teardown();
ReadBufferManager.getBufferManager().testResetReadBufferManager();
}

private AbfsRestOperation getMockRestOp() {
AbfsRestOperation op = mock(AbfsRestOperation.class);
AbfsHttpOperation httpOp = mock(AbfsHttpOperation.class);
Expand All @@ -106,7 +112,6 @@ private AbfsClient getMockAbfsClient() {
private AbfsInputStream getAbfsInputStream(AbfsClient mockAbfsClient,
String fileName) throws IOException {
AbfsInputStreamContext inputStreamContext = new AbfsInputStreamContext(-1);
inputStreamContext.isReadAheadEnabled(true);
// Create AbfsInputStream with the client instance
AbfsInputStream inputStream = new AbfsInputStream(
mockAbfsClient,
Expand All @@ -132,7 +137,6 @@ public AbfsInputStream getAbfsInputStream(AbfsClient abfsClient,
boolean alwaysReadBufferSize,
int readAheadBlockSize) throws IOException {
AbfsInputStreamContext inputStreamContext = new AbfsInputStreamContext(-1);
inputStreamContext.isReadAheadEnabled(true);
// Create AbfsInputStream with the client instance
AbfsInputStream inputStream = new AbfsInputStream(
abfsClient,
Expand Down Expand Up @@ -495,6 +499,63 @@ public void testSuccessfulReadAhead() throws Exception {
checkEvictedStatus(inputStream, 0, true);
}

/**
* This test expects InProgressList is not purged by the inputStream close.
*/
@Test
public void testStreamPurgeDuringReadAheadCallExecuting() throws Exception {
AbfsClient client = getMockAbfsClient();
AbfsRestOperation successOp = getMockRestOp();
final Long serverCommunicationMockLatency = 3_000L;
final Long readBufferTransferToInProgressProbableTime = 1_000L;
final Integer readBufferQueuedCount = 3;

Mockito.doAnswer(invocationOnMock -> {
//sleeping thread to mock the network latency from client to backend.
Thread.sleep(serverCommunicationMockLatency);
return successOp;
})
.when(client)
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@snvijaya snvijaya Dec 1, 2022

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The test is trying to unit test a bigger scope of existing inprogress buffer moving to completed list. Will be nice to scope the test to inProgressList and freelist counts, before and after close.

At this client.read() mock, I would suggest mocks that will invoke a large sleep for each read. That way after queueReadAheads call and a 1 sec sleep, 3 buffers will be stuck inProgessList and the freeeList should show 13 free. The asserts should continue to hold to same numbers post close as well.

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@saxenapranav saxenapranav Dec 1, 2022

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Have taken the change of sleep and assertion on freeList also included in the tests.

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@steveloughran steveloughran Dec 1, 2022

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this is very brittle being timing based. normally I'd say "no" here, but I know I have a forthcoming pr which uses object.wait/notify to synchronize
https://github.com/apache/hadoop/pull/5117/files#diff-e829dbaa29faf05ae0b331439e9aec3cd02248464a097c86a0227783337b9b76R370

if this test causes problems it should do the same

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@snvijaya snvijaya Dec 2, 2022

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Hi Steve, the sleep time on these mock threads are meant to hold the thread blocked while the test goes ahead with asserts after queuing reads and asserts after close. The sleep of 1 second (which will block the main test thread) after queueing reads has been consistent with the timing expectations with pre-existing tests in this class doing the same, however I agree that this test has lot more going beyond the close which needs time synchronization, which can make the test brittle.

Hi Pranav, The test asserts post line 566 starting from 3 sec sleep are validations for correct movement of inprogress buffers to completed list and their evictions, which is a functionality that this PR change does not interfere. I would suggest that we take them out and evaluate if pre-existing test coverage doesnt handle it already. If there are gaps, lets take it in separate PR.

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@saxenapranav saxenapranav Dec 2, 2022

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Thanks. I have removed the assertion on inProgress to completedList and the eviction.

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@steveloughran steveloughran Dec 2, 2022

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it may be slow, but at least there's no assertion that something finishes before a specific timeout. those are the tests which really have problems on slow networks/overloaded systems

.read(any(String.class), any(Long.class), any(byte[].class),
any(Integer.class), any(Integer.class), any(String.class),
any(String.class), any(TracingContext.class));

AbfsInputStream inputStream = getAbfsInputStream(client,
"testSuccessfulReadAhead.txt");
queueReadAheads(inputStream);

final ReadBufferManager readBufferManager
= ReadBufferManager.getBufferManager();

final int readBufferTotal = readBufferManager.getNumBuffers();

//Sleeping to give ReadBufferWorker to pick the readBuffers for processing.
Thread.sleep(readBufferTransferToInProgressProbableTime);

Assertions.assertThat(readBufferManager.getInProgressCopiedList())
.describedAs("InProgressList should have " + readBufferQueuedCount + " elements")
.hasSize(readBufferQueuedCount);
final int freeListBufferCount = readBufferTotal - readBufferQueuedCount;
Assertions.assertThat(readBufferManager.getFreeListCopy())
.describedAs("FreeList should have " + freeListBufferCount + "elements")
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@steveloughran steveloughran Dec 6, 2022

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you can actually use string.format patterns here; most relevant for on demand toString calls which are more expensive. I'm not worrying about it here though

.hasSize(freeListBufferCount);
Assertions.assertThat(readBufferManager.getCompletedReadListCopy())
.describedAs("CompletedList should have 0 elements")
.hasSize(0);

inputStream.close();
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@steveloughran steveloughran Dec 6, 2022

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the problem with the close() here is that it will only be reached if the assertions hold. if anything goes wrong, an exception is raised and the stream kept open, with whatever resources it consumes.

it should be closed in a finally block or the stream opened in a try-with-resources clause. thanks


Assertions.assertThat(readBufferManager.getInProgressCopiedList())
.describedAs("InProgressList should have " + readBufferQueuedCount + " elements")
.hasSize(readBufferQueuedCount);
Assertions.assertThat(readBufferManager.getCompletedReadListCopy())
.describedAs("CompletedList should have 0 elements")
.hasSize(0);
Assertions.assertThat(readBufferManager.getFreeListCopy())
.describedAs("FreeList should have " + freeListBufferCount + " elements")
.hasSize(freeListBufferCount);
}

/**
* This test expects ReadAheadManager to throw exception if the read ahead
* thread had failed within the last thresholdAgeMilliseconds.
Expand Down