Flaky test ApiUploadTest::testUploadChunks()
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	tstarling
	Sat, Mar 18, 12:32 AM

Description

Example console triggered by gerrit 900459.

01:19:51 1) ApiUploadTest::testUploadChunks
01:19:51 ApiUsageException: The file /tmp/localcopy_14095242b63b.jpg does not exist.
...
01:19:51 [wfDebug] [debug] UploadStash::stashFile tried to stash file at '/tmp/localcopy_14095242b63b.jpg', but it doesn't exist {"private":false}

I've confirmed that it is possible to trigger deletion of the relevant temporary file while the file is still in use, using gc_collect_cycles(), which causes the TempFSFile to be destroyed.

Concatenation is finished by around line 607541 of the debug log, but it tries to stash again at line 607674. Why? The error indicates that performStash('critical') was called, so it must have been from getChunkResult() or getStashResult().

Details

Project	Branch	Lines +/-	Subject
mediawiki/core	REL1_40	+14 -11	TempFSFile: Keep the WeakMap alive
mediawiki/core	REL1_39	+14 -11	TempFSFile: Keep the WeakMap alive
mediawiki/core	master	+14 -11	TempFSFile: Keep the WeakMap alive

Customize query in gerrit

Related Objects

Mentioned In: T332397: Frequent flakiness from UploadFromUrlTest::testSyncDownload

Event Timeline

tstarling created this task.Sat, Mar 18, 12:32 AM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptSat, Mar 18, 12:32 AM

tstarling mentioned this in T332397: Frequent flakiness from UploadFromUrlTest::testSyncDownload.Sat, Mar 18, 12:34 AM

Maintenance_bot added a project: Commons.Sat, Mar 18, 12:46 AM

The error indicates that performStash('critical') was called, so it must have been from getChunkResult() or getStashResult().

Actually the test fails with the error message backend-fail-notexists, it's not failing in getChunkResult() or getStashResult().

This leads us to a very plausible model for reproducible failure:

diff --git a/includes/libs/filebackend/fileop/StoreFileOp.php b/includes/libs/filebackend/fileop/StoreFileOp.php
index 76cc4b6c494..4c0942ec00f 100644
--- a/includes/libs/filebackend/fileop/StoreFileOp.php
+++ b/includes/libs/filebackend/fileop/StoreFileOp.php
@@ -37,6 +37,8 @@ class StoreFileOp extends FileOp {
        }
 
        protected function doPrecheck( array &$predicates ) {
+               wfDebug( __METHOD__ . "({$this->params['src']})" );
+               gc_collect_cycles();
                $status = StatusValue::newGood();
 
                // Check if the source file exists in the file system and is not too big