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List:       openjdk-2d-dev
Subject:    Re: RFR: 8331142: Add test for number of loader threads in BasicDirectoryModel [v2]
From:       Tejesh R <tr () openjdk ! org>
Date:       2024-04-30 11:36:05
Message-ID: gw-3gB_WOiEIkrv04bT2TKVe0gOTCg8Vm6I2wz5Xg98=.c36d6ae2-b3f0-4a2b-ae7e-97b6247562ef () github ! com
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On Mon, 29 Apr 2024 19:59:18 GMT, Alexey Ivanov <aivanov@openjdk.org> wrote:

> > This PR provides a regression test for \
> > [JDK-8325179](https://bugs.openjdk.org/browse/JDK-8325179): _Race in \
> > BasicDirectoryModel.validateFileCache_ reviewed in #18111. 
> > The test is inspired and based on `ConcurrentModification` that I wrote for \
> > [JDK-8327137](https://bugs.openjdk.org/browse/JDK-8327137) / \
> > [JDK-8323670](https://bugs.openjdk.org/browse/JDK-8323670). 
> > **How the test works**
> > 
> > The test creates a temporary directory in the current directory and creates a \
> > number of files in it. (The number of files is controlled by `NUMBER_OF_THREADS` \
> > constant). Then the test creates `JFileChooser` in the temporary directory. 
> > The test starts several scanner threads, the number is controlled by \
> > `NUMBER_OF_THREADS`, which repeatedly call \
> > `fileChooser.rescanCurrentDirectory()`. This results in calling \
> > `BasicDirectoryModel.validateFileCache` which starts a background thread — \
> > "Basic L&F File Loading Thread" — to enumerate the files. 
> > The test runner thread and scanner threads are synchronised with `CyclicBarrier`, \
> > this ensures all the scanner threads start at the same time. After a short delay, \
> > the runner thread takes a snapshot of live threads. After a longer delay, the \
> > operation is repeated. See the `getThreadSnapshot` method. (The number of \
> > snapshots is controlled by `SNAPSHOTS` constant.) 
> > The number of File Loading Threads in each snapshot is counted. There should be \
> > no more than two threads. It is possible that thread two such threads after \
> > JDK-8325179 is fixed: the existing thread is interrupted but hasn't exited yet, \
> > and a new thread is already created. 
> > The test fails consistently without the fix for JDK-8325179. On Windows, the \
> > output looks like this: 
> > 
> > Number of snapshots: 20
> > Number of snapshots where number of loader threads:
> > = 1: 0
> > = 2: 0
> > > 2: 20
> > java.lang.RuntimeException: Detected 20 snapshots with several loading threads
> > at LoaderThreadCount.runTest(LoaderThreadCount.java:132)
> > at LoaderThreadCount.wrapper(LoaderThreadCount.java:72)
> > at java.base/java.lang.Thread.run(Thread.java:1583)
> > 
> > 
> > On Linux and macOS, there's more variation, for example I got the following \
> > output on one of Linux systems: 
> > 
> > Number of snapshots: 15
> > Number of snapshots where number of loader threads:
> > = 1: 7
> > = 2: 2
> > > 2: 6
> > 
> > 
> > The test passes on the builds where JDK-8325179 is present.
> 
> Alexey Ivanov has updated the pull request incrementally with one additional commit \
> since the last revision: 
> Suppress throwing exceptions while deleting files

Looks Good to me.

Marked as reviewed by tr (Committer).

-------------

Marked as reviewed by tr (Committer).

PR Review: https://git.openjdk.org/jdk/pull/18957#pullrequestreview-2031028809
PR Review: https://git.openjdk.org/jdk/pull/18957#pullrequestreview-2031029437


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