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Correctly log exceptions that are thrown during cache prewarming #74419

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Merged
merged 1 commit into from
Jun 28, 2021
Merged

Correctly log exceptions that are thrown during cache prewarming #74419

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19 changes: 15 additions & 4 deletions ...n/java/org/elasticsearch/xpack/searchablesnapshots/store/SearchableSnapshotDirectory.java
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Original file line number Diff line number Diff line change
Expand Up @@ -506,8 +506,9 @@ private void prewarmCache(ActionListener<Void> listener) {
}, listener::onFailure), snapshot().totalFileCount());

for (BlobStoreIndexShardSnapshot.FileInfo file : snapshot().indexFiles()) {
if (file.metadata().hashEqualsContents() || isExcludedFromCache(file.physicalName())) {
if (file.metadata().hashEqualsContents()) {
boolean hashEqualsContents = file.metadata().hashEqualsContents();
if (hashEqualsContents || isExcludedFromCache(file.physicalName())) {
if (hashEqualsContents) {
recoveryState.getIndex().addFileDetail(file.physicalName(), file.length(), true);
} else {
recoveryState.ignoreFile(file.physicalName());
Expand All @@ -516,17 +517,24 @@ private void prewarmCache(ActionListener<Void> listener) {
continue;
}
recoveryState.getIndex().addFileDetail(file.physicalName(), file.length(), false);
boolean submitted = false;
try {
final IndexInput input = openInput(file.physicalName(), CachedBlobContainerIndexInput.CACHE_WARMING_CONTEXT);
assert input instanceof CachedBlobContainerIndexInput : "expected cached index input but got " + input.getClass();

final int numberOfParts = file.numberOfParts();
final StepListener<Collection<Void>> fileCompletionListener = new StepListener<>();
fileCompletionListener.whenComplete(voids -> input.close(), e -> IOUtils.closeWhileHandlingException(input));
fileCompletionListener.addListener(completionListener.map(voids -> null));
fileCompletionListener.whenComplete(voids -> {
logger.debug("{} file [{}] prewarmed", shardId, file.physicalName());
input.close();
}, e -> {
logger.warn(() -> new ParameterizedMessage("{} prewarming failed for file [{}]", shardId, file.physicalName()), e);
IOUtils.closeWhileHandlingException(input);
});

final GroupedActionListener<Void> partsListener = new GroupedActionListener<>(fileCompletionListener, numberOfParts);

submitted = true;
for (int p = 0; p < numberOfParts; p++) {
final int part = p;
queue.add(Tuple.tuple(partsListener, () -> {
Expand Down Expand Up @@ -555,6 +563,9 @@ private void prewarmCache(ActionListener<Void> listener) {
}
} catch (IOException e) {
logger.warn(() -> new ParameterizedMessage("{} unable to prewarm file [{}]", shardId, file.physicalName()), e);
if (submitted == false) {
completionListener.onFailure(e);
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@henningandersen henningandersen Jun 23, 2021

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I think this attempts to ensure that the recovery state moves to DONE? I guess that is more correct than FINALIZE, but I think we should add a test for it.
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@tlrx tlrx Jun 24, 2021

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It attempts to complete the grouped listener but has not other side effect besides logging a warning message if the shard is a relocation target:

elasticsearch/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/allocation/SearchableSnapshotIndexEventListener.java

Lines 78 to 90 in a5d2251

if (success && shardRouting.isRelocationTarget()) {
final Runnable preWarmCondition = indexShard.addCleanFilesDependency();
preWarmListener.whenComplete(v -> preWarmCondition.run(), e -> {
logger.warn(
new ParameterizedMessage(
"pre-warm operation failed for [{}] while it was the target of primary relocation [{}]",
shardRouting.shardId(),
shardRouting
),
e
);
preWarmCondition.run();
});

I'm OK with leaving the recovery state in FINALIZE as this is what allowed to detect a non-fully prewarmed shard at the first place. I think that adding more logs would have helped to troubleshoot some issues when accessing repository files.
}
}
}

Expand Down