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Slack merge throttling params for fewer merge tasks #126016

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Merged
merged 6 commits into from
Apr 2, 2025
Merged

Slack merge throttling params for fewer merge tasks #126016

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aeea9fb
params adjust
albertzaharovits Apr 1, 2025
ea6c186
Merge branch 'main' into merge-throughput-parameter-adjust
albertzaharovits Apr 1, 2025
71da92a
Review
albertzaharovits Apr 1, 2025
0b538e5
[CI] Auto commit changes from spotless
Apr 1, 2025
d1aa26c
Update server/src/test/java/org/elasticsearch/index/engine/ThreadPool…
albertzaharovits Apr 2, 2025
c702fb4
Merge branch 'main' into merge-throughput-parameter-adjust
albertzaharovits Apr 2, 2025
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20 changes: 6 additions & 14 deletions server/src/main/java/org/elasticsearch/index/engine/ThreadPoolMergeExecutorService.java
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Original file line number Diff line number Diff line change
Expand Up @@ -87,8 +87,10 @@ public class ThreadPoolMergeExecutorService {
private ThreadPoolMergeExecutorService(ThreadPool threadPool) {
this.executorService = threadPool.executor(ThreadPool.Names.MERGE);
this.maxConcurrentMerges = threadPool.info(ThreadPool.Names.MERGE).getMax();
this.concurrentMergesFloorLimitForThrottling = maxConcurrentMerges * 2;
this.concurrentMergesCeilLimitForThrottling = maxConcurrentMerges * 4;
// the intent here is to throttle down whenever we submit a task and no other task is running
this.concurrentMergesFloorLimitForThrottling = 2;
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Can we put a comment here that this means to only decrease throttle rate when we submit a task and no other tasks are running?

this.concurrentMergesCeilLimitForThrottling = maxConcurrentMerges * 2;
assert concurrentMergesFloorLimitForThrottling <= concurrentMergesCeilLimitForThrottling;
}
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Perhaps assert that concurrentMergesCeilLimitForThrottling >= concurrentMergesFloorLimitForThrottling - I feel like it adds readabililty.


boolean submitMergeTask(MergeTask mergeTask) {
Expand Down Expand Up @@ -230,10 +232,10 @@ private static long newTargetIORateBytesPerSec(
);
} else if (currentlySubmittedIOThrottledMergeTasks > concurrentMergesCeilLimitForThrottling
&& currentTargetIORateBytesPerSec < MAX_IO_RATE.getBytes()) {
// increase target IO rate by 10% (capped)
// increase target IO rate by 20% (capped)
newTargetIORateBytesPerSec = Math.min(
MAX_IO_RATE.getBytes(),
currentTargetIORateBytesPerSec + currentTargetIORateBytesPerSec / 10L
currentTargetIORateBytesPerSec + currentTargetIORateBytesPerSec / 5L
);
} else {
newTargetIORateBytesPerSec = currentTargetIORateBytesPerSec;
Expand Down Expand Up @@ -295,14 +297,4 @@ long getTargetIORateBytesPerSec() {
int getMaxConcurrentMerges() {
return maxConcurrentMerges;
}

// exposed for tests
int getConcurrentMergesFloorLimitForThrottling() {
return concurrentMergesFloorLimitForThrottling;
}

// exposed for tests
int getConcurrentMergesCeilLimitForThrottling() {
return concurrentMergesCeilLimitForThrottling;
}
}
37 changes: 17 additions & 20 deletions server/src/test/java/org/elasticsearch/index/engine/ThreadPoolMergeExecutorServiceTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -219,18 +219,16 @@ public void testTargetIORateChangesWhenSubmittingMergeTasks() throws Exception {
}
long newIORate = threadPoolMergeExecutorService.getTargetIORateBytesPerSec();
if (supportsIOThrottling) {
if (submittedIOThrottledMergeTasks.get() < threadPoolMergeExecutorService
.getConcurrentMergesFloorLimitForThrottling()) {
// assert the IO rate decreases, with a floor limit, when there are few merge tasks enqueued
if (submittedIOThrottledMergeTasks.get() < 2) {
// assert the IO rate decreases, with a floor limit, when there is just a single merge task running
assertThat(newIORate, either(is(MIN_IO_RATE.getBytes())).or(lessThan(currentIORate)));
} else if (submittedIOThrottledMergeTasks.get() > threadPoolMergeExecutorService
.getConcurrentMergesCeilLimitForThrottling()) {
// assert the IO rate increases, with a ceiling limit, when there are many merge tasks enqueued
assertThat(newIORate, either(is(MAX_IO_RATE.getBytes())).or(greaterThan(currentIORate)));
} else {
// assert the IO rate does NOT change when there are a couple of merge tasks enqueued
assertThat(newIORate, equalTo(currentIORate));
}
} else if (submittedIOThrottledMergeTasks.get() > threadPoolMergeExecutorService.getMaxConcurrentMerges() * 2) {
// assert the IO rate increases, with a ceiling limit, when there are many merge tasks enqueued
assertThat(newIORate, either(is(MAX_IO_RATE.getBytes())).or(greaterThan(currentIORate)));
} else {
// assert the IO rate does NOT change when there are a couple of merge tasks enqueued
assertThat(newIORate, equalTo(currentIORate));
}
} else {
// assert the IO rate does not change, when the merge task doesn't support IO throttling
assertThat(newIORate, equalTo(currentIORate));
Expand Down Expand Up @@ -375,17 +373,16 @@ private void testIORateAdjustedForSubmittedTasks(
initialTasksCounter--;
threadPoolMergeExecutorService.submitMergeTask(mergeTask);
long newTargetIORateLimit = threadPoolMergeExecutorService.getTargetIORateBytesPerSec();
if (currentlySubmittedMergeTaskCount.get() < threadPoolMergeExecutorService.getConcurrentMergesFloorLimitForThrottling()) {
if (currentlySubmittedMergeTaskCount.get() < 2) {
// assert the IO rate decreases, with a floor limit, when there are few merge tasks enqueued
assertThat(newTargetIORateLimit, either(is(MIN_IO_RATE.getBytes())).or(lessThan(targetIORateLimit.get())));
} else if (currentlySubmittedMergeTaskCount.get() > threadPoolMergeExecutorService
.getConcurrentMergesCeilLimitForThrottling()) {
// assert the IO rate increases, with a ceiling limit, when there are many merge tasks enqueued
assertThat(newTargetIORateLimit, either(is(MAX_IO_RATE.getBytes())).or(greaterThan(targetIORateLimit.get())));
} else {
// assert the IO rate does change, when there are a couple of merge tasks enqueued
assertThat(newTargetIORateLimit, equalTo(targetIORateLimit.get()));
}
} else if (currentlySubmittedMergeTaskCount.get() > threadPoolMergeExecutorService.getMaxConcurrentMerges() * 2) {
// assert the IO rate increases, with a ceiling limit, when there are many merge tasks enqueued
assertThat(newTargetIORateLimit, either(is(MAX_IO_RATE.getBytes())).or(greaterThan(targetIORateLimit.get())));
} else {
// assert the IO rate does not change, when there are a couple of merge tasks enqueued
assertThat(newTargetIORateLimit, equalTo(targetIORateLimit.get()));
}
targetIORateLimit.set(newTargetIORateLimit);
} else {
// execute already submitted merge task
Expand Down