Disable PHP OPcache JIT by default - #1653
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JIT tracing mode in PHP 8.3 has known memory corruption bugs that can cause recurring PHP-FPM crashes with ~4GB allocation attempts. WordPress workloads are I/O-bound and see negligible benefit from JIT, making the risk/reward unfavorable. JIT can be re-enabled via group_vars by setting php_opcache_jit and php_opcache_jit_buffer_size. Also consolidates JIT directives into 10-opcache.ini.j2 instead of splitting them across two config files. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
swalkinshaw
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Mar 18, 2026
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Unfortunate but makes sense for now
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Summary
php_opcache_jit: 'disable',php_opcache_jit_buffer_size: 0)10-opcache.ini.j2(previously split across10-opcache.ini.j2andphp-fpm.ini.j2)Context
PHP 8.3's JIT tracing mode has known memory corruption bugs that cause recurring PHP-FPM worker crashes. The crash signature is a consistent ~4GB allocation attempt (
0x100040000), which is a JIT corruption artifact — not real application memory demand.Reported here: https://discourse.roots.io/t/php-8-3-jit-tracing-recurring-crash-at-theme-php-325-4gb-allocation/30241
Since Trellis defaults to PHP 8.3 with JIT tracing enabled, all sites on default configuration carry this risk. WordPress workloads are overwhelmingly I/O-bound and see negligible real-world performance benefit from JIT, making it a poor tradeoff.
OPcache bytecode caching remains fully enabled and unaffected.
Re-enabling JIT
Users who want JIT can opt in via
group_vars:🤖 Generated with Claude Code