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Posted to issues@flink.apache.org by GitBox <gi...@apache.org> on 2022/07/20 09:55:47 UTC
[GitHub] [flink] TanYuxin-tyx opened a new pull request, #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
TanYuxin-tyx opened a new pull request, #20320:
URL: https://github.com/apache/flink/pull/20320
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## What is the purpose of the change
Currently, the SortMergeResultPartitionReadScheduler always gets all active subpartition readers and read at most one data region for them. It is common that some subpartitions are requested before others and their region indexes are ahead of others.
If all region data of a subpartition can be read in one round, some subpartition readers will always be ahead of others which will cause random IO.
This patch fixes this case by polling one subpartition reader at a time.
## Brief change log
- *Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially.*
## Verifying this change
This change is already covered by existing tests, such as *SortMergeResultPartitionReadSchedulerTest*.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no**)
- The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (yes / **no**)
- The serializers: (yes / **no** / don't know)
- The runtime per-record code paths (performance sensitive): (yes / **no** / don't know)
- Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / **no** / don't know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? (yes / **no**)
- If yes, how is the feature documented? (**not applicable** / docs / JavaDocs / not documented)
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[GitHub] [flink] flinkbot commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
flinkbot commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1190085113
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## CI report:
* a830ee22681f80b0f556aee94ef63694fa110d44 UNKNOWN
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1198019040
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1191498330
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1191118892
> @TanYuxin-tyx, thanks for your contribution, this bug-fix looks good to me overall. I left some comments, please take a look~
@reswqa Thanks a lot for reviewing the PR, I have updated the code and fixed the comments.
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[GitHub] [flink] reswqa commented on a diff in pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
reswqa commented on code in PR #20320:
URL: https://github.com/apache/flink/pull/20320#discussion_r925823372
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -152,12 +160,34 @@ class SortMergeResultPartitionReadScheduler implements Runnable, BufferRecycler
@Override
public synchronized void run() {
- Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders();
-
- Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>();
+ Queue<MemorySegment> buffers;
+ try {
+ buffers = allocateBuffers();
+ } catch (Throwable throwable) {
+ // fail all pending subpartition readers immediately if any exception occurs
+ LOG.error("Failed to request buffers for data reading.", throwable);
+ failSubpartitionReaders(getAllReaders(), throwable);
Review Comment:
`release` and `releaseSubpartitionReader` should take care of `sortedReaders ` also. These two method will add reader to `failedReaders` set, we should filter out useless readers as soon as possible. For example, may not be the best solution, we can add check to `getNextReaderToRead`, when the polled reader contains in `failedReaders`, ignore it and poll next until meet the reader not failed. But `removeFinishedAndFailedReaders` will clear `failedReaders`, It is possible that some failed readers have not been polled from `sortedReaders` in this round of scheduling, we can remove the failed reader from `failedReaders` in `getNextReaderToRead` every time polled reader is failed.
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1191110379
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[GitHub] [flink] reswqa commented on a diff in pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
reswqa commented on code in PR #20320:
URL: https://github.com/apache/flink/pull/20320#discussion_r925823372
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -152,12 +160,34 @@ class SortMergeResultPartitionReadScheduler implements Runnable, BufferRecycler
@Override
public synchronized void run() {
- Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders();
-
- Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>();
+ Queue<MemorySegment> buffers;
+ try {
+ buffers = allocateBuffers();
+ } catch (Throwable throwable) {
+ // fail all pending subpartition readers immediately if any exception occurs
+ LOG.error("Failed to request buffers for data reading.", throwable);
+ failSubpartitionReaders(getAllReaders(), throwable);
Review Comment:
`release` and `releaseSubpartitionReader` should take care of `sortedReaders ` also. These two method will add reader to `failedReaders` set, we should filter out useless readers as soon as possible. For example, may not be the best solution, we can add check to `getNextReaderToRead`, when the polled reader contains in `failedReaders`, ignore it and poll next until meet the reader not failed. But `removeFinishedAndFailedReaders` will clear `failedReaders`, It is possible that some failed readers have not been polled from `sortedReaders` in this round of scheduling. We can remove the failed reader from `failedReaders` in `getNextReaderToRead` every time polled reader is failed, instead of in `removeFinishedAndFailedReaders`.
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[GitHub] [flink] reswqa commented on a diff in pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
reswqa commented on code in PR #20320:
URL: https://github.com/apache/flink/pull/20320#discussion_r925823372
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -152,12 +160,34 @@ class SortMergeResultPartitionReadScheduler implements Runnable, BufferRecycler
@Override
public synchronized void run() {
- Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders();
-
- Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>();
+ Queue<MemorySegment> buffers;
+ try {
+ buffers = allocateBuffers();
+ } catch (Throwable throwable) {
+ // fail all pending subpartition readers immediately if any exception occurs
+ LOG.error("Failed to request buffers for data reading.", throwable);
+ failSubpartitionReaders(getAllReaders(), throwable);
Review Comment:
`release` and `releaseSubpartitionReader` should take care of `sortedReaders ` also.
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[GitHub] [flink] wsry merged pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
wsry merged PR #20320:
URL: https://github.com/apache/flink/pull/20320
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[GitHub] [flink] reswqa commented on a diff in pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
reswqa commented on code in PR #20320:
URL: https://github.com/apache/flink/pull/20320#discussion_r925818232
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -152,12 +160,34 @@ class SortMergeResultPartitionReadScheduler implements Runnable, BufferRecycler
@Override
public synchronized void run() {
- Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders();
-
- Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>();
+ Queue<MemorySegment> buffers;
+ try {
+ buffers = allocateBuffers();
+ } catch (Throwable throwable) {
+ // fail all pending subpartition readers immediately if any exception occurs
+ LOG.error("Failed to request buffers for data reading.", throwable);
+ failSubpartitionReaders(getAllReaders(), throwable);
Review Comment:
If a failed reader not removed from `sortedBuffers` in time, It can only be removed after the next poll, but this failed reader will read data from disk int that case, which is an unnecessary extra overhead. IMO, we need clear `sortedReaders` when `allocateBuffers` throw exception.
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -283,13 +284,26 @@ private void mayNotifyReleased() {
}
}
- private Queue<SortMergeSubpartitionReader> getAvailableReaders() {
+ private Queue<SortMergeSubpartitionReader> getAllReaders() {
synchronized (lock) {
if (isReleased) {
return new ArrayDeque<>();
}
+ return new ArrayDeque<>(allReaders);
+ }
+ }
- return new PriorityQueue<>(allReaders);
+ @Nullable
+ private SortMergeSubpartitionReader getNextReaderToRead(
Review Comment:
```suggestion
private SortMergeSubpartitionReader addPreviousAndGetNextReader(
```
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -152,12 +160,34 @@ class SortMergeResultPartitionReadScheduler implements Runnable, BufferRecycler
@Override
public synchronized void run() {
- Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders();
-
- Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>();
+ Queue<MemorySegment> buffers;
+ try {
+ buffers = allocateBuffers();
+ } catch (Throwable throwable) {
+ // fail all pending subpartition readers immediately if any exception occurs
+ LOG.error("Failed to request buffers for data reading.", throwable);
+ failSubpartitionReaders(getAllReaders(), throwable);
Review Comment:
`release` and `releaseSubpartitionReader` should take care of `sortedReaders ` also. These two method will add reader to `failedReaders` set, I suggest add check to `getNextReaderToRead`, when the polled reader contains in `failedReaders`, we can ignore it and poll next until meet the reader not failed.
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[GitHub] [flink] TanYuxin-tyx commented on a diff in pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on code in PR #20320:
URL: https://github.com/apache/flink/pull/20320#discussion_r926313613
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -152,12 +160,34 @@ class SortMergeResultPartitionReadScheduler implements Runnable, BufferRecycler
@Override
public synchronized void run() {
- Queue<SortMergeSubpartitionReader> availableReaders = getAvailableReaders();
-
- Queue<MemorySegment> buffers = allocateBuffers(availableReaders);
+ Set<SortMergeSubpartitionReader> finishedReaders = new HashSet<>();
+ Queue<MemorySegment> buffers;
+ try {
+ buffers = allocateBuffers();
+ } catch (Throwable throwable) {
+ // fail all pending subpartition readers immediately if any exception occurs
+ LOG.error("Failed to request buffers for data reading.", throwable);
+ failSubpartitionReaders(getAllReaders(), throwable);
Review Comment:
@reswqa Thanks for helping review. Good point.
In order to clear the reader in `sortedBuffers` in time, I added a check whether the reader is in `failedReaders` in the method `addPreviousAndGetNextReader`.
In addtion, when `allReaders` is empty, the `sortedBuffers` will be cleared in `removeFinishedAndFailedReaders`.
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1199042877
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[GitHub] [flink] TanYuxin-tyx commented on a diff in pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on code in PR #20320:
URL: https://github.com/apache/flink/pull/20320#discussion_r926310001
##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/SortMergeResultPartitionReadScheduler.java:
##########
@@ -283,13 +284,26 @@ private void mayNotifyReleased() {
}
}
- private Queue<SortMergeSubpartitionReader> getAvailableReaders() {
+ private Queue<SortMergeSubpartitionReader> getAllReaders() {
synchronized (lock) {
if (isReleased) {
return new ArrayDeque<>();
}
+ return new ArrayDeque<>(allReaders);
+ }
+ }
- return new PriorityQueue<>(allReaders);
+ @Nullable
+ private SortMergeSubpartitionReader getNextReaderToRead(
Review Comment:
OK, renamed it.
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1191438366
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[GitHub] [flink] TanYuxin-tyx commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
TanYuxin-tyx commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1199057289
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[GitHub] [flink] wsry commented on pull request #20320: [FLINK-28519][network] Fix the bug that SortMergeResultPartitionReadScheduler may not read data sequentially
Posted by GitBox <gi...@apache.org>.
wsry commented on PR #20320:
URL: https://github.com/apache/flink/pull/20320#issuecomment-1199191376
@TanYuxin-tyx Thanks for the change and review from @reswqa . LGTM.
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