Pipeline buffering and upload in S3 multi-upload #10729
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findepi
approved these changes
Jan 21, 2022
plugin/trino-hive/src/main/java/io/trino/plugin/hive/s3/TrinoS3FileSystem.java
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AC |
findepi
approved these changes
Jan 21, 2022
plugin/trino-hive/src/main/java/io/trino/plugin/hive/s3/TrinoS3FileSystem.java
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| if (aborted) { | ||
| return; | ||
| } | ||
| aborted = true; |
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will drop abort change for now to keep this PR focused.
| @@ -1478,6 +1478,7 @@ public synchronized void progressChanged(ProgressEvent progressEvent) | |||
| private int bufferSize; | |||
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| private boolean failed; | |||
| private boolean multipartUploadStarted; | |||
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there are effectively 2 threads here
- calling thread (one thread; as it's not meant to be thread-safe)
- the background uploading thread (because we never submit another task to executor until previous finished)
let's document, for each field, which thread(s) use it
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done.
And dropped other commits, replacing with commit message
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| // We use multipartUploadStarted flag here instead uploadId.ifPresent() because visibility of latter one is not | ||
| // ensured here. It is mutated in other thread spawned by uploadExecutor.submit below |
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This comment is understandable from reviewer and historical perspective.
We wouldn't write such comment if we had the code right from the start, which suggests the comment is more suitable for the commit message than the code.
linzebing
approved these changes
Jan 21, 2022
With code restructuring we needed to add separate multipartUploadStarted flag which is both written and read from main thread (not an upload) thread. With `waitForPreviousUploadFinish` moved below we lost memory-barrier between main and upload thread and we could no longer use `uploadId` to determine if multipart upload was already started. Co-authored-by: Łukasz Osipiuk <[email protected]>
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Rework of: #10180
Original PR desc:
It turned out that this PR results in corrupted writes to S3 (#10710).
The problem came from the fact that with
waitForPreviousUploadFinishcall moved from the very beginning offlushBuffermethod further down, the check:was no longer valid.
One call to
flushBuffercould initiate the multipart upload, but the next call toflushBuffercould still observeuploadIdas not set (there was no memory barrier between setting and reading threads).Thanks @findepi for chat on this.
Co-authored-by: Łukasz Osipiuk [email protected]
Fixes #10710