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Give each mvn.cmd run its own temp directory - #13717
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%RANDOM% is seeded from the clock once per cmd.exe, so mvn.cmd processes started in the same second named their jvm.config and version temp files alike. Since the JVM reads the jvm.config file as an @argfile and it is kept until the JVM exits, parallel builds ran with each other's JVM arguments. mkdir fails on an existing name, so a retry loop yields a private directory.
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Oct 28, 2026
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Verified fix for the %RANDOM% seed-collision race: the :mkTempDir subroutine uses mkdir atomicity with a 100-iteration retry loop, ensuring concurrent processes never share a temp file. All cleanup paths (normal exit, java failure, parser failure, JVM error) are covered. One nit below.
This review was generated by an AI agent, Hermès on behalf of @gnodet.
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| rd /s /q "%VERSION_SETTINGS_DIR%" 2>nul | ||
| set "VERSION_SETTINGS_TEMP=" |
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After rd /s /q removes the directory, VERSION_SETTINGS_DIR stays defined (it still holds the now-deleted path). Only VERSION_SETTINGS_TEMP is cleared. For symmetry with the initial set "VERSION_SETTINGS_DIR=" at the top of the script, clear it here too.
Suggested change
| rd /s /q "%VERSION_SETTINGS_DIR%" 2>nul | |
| set "VERSION_SETTINGS_TEMP=" | |
| rd /s /q "%VERSION_SETTINGS_DIR%" 2>nul | |
| set "VERSION_SETTINGS_DIR=" | |
| set "VERSION_SETTINGS_TEMP=" |
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Fixes #13716.
mvn.cmdnow creates itsjvm.configargfile and itsmvn -vsettings dump inside a directory made by a new:mkTempDirroutine.mkdirfails when the name already exists, so processes that start in the same second, and therefore draw the same%RANDOM%values, retry with the next values instead of sharing a file. The directory is removed where the file used to be deleted.JVM_CONFIG_DIRandJVM_CONFIG_TEMPare cleared at the start, so a value inherited from the environment is never used or deleted.I have no Windows machine, so this has not been run outside CI. The Windows integration-test jobs on this PR run
MavenITmng4559MultipleJvmArgsTest, which failed in three of four failedmasterbuilds on 2026-10-22 and 2026-10-23; one green run does not prove a race fixed.