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Starting with version 8, PHP introduced a just-in-time (JIT) compiler, which allows the Polar Signals Agent to profile it once a few flags are enabled.

  • -d (optional but recommended)
  • -d opcache.enable_cli=1 (optional but recommended)
  • -d opcache.jit=function: Enables the just-in-time (JIT) compiler
  • -d opcache.jit_buffer_size=64M: Configures the JIT so it doesn't recompile too often
  • -d opcache.jit_debug=0x20: Configures the JIT to generate a Linux jitdump, which is required to translate addresses to human-readable function names, file names, and line numbers.
  • -d opcache.jit_debug=0x10: (Not Recommended) Alternative to the previous flag, configures the JIT to write metadata to /tmp/perf-<PID>.map. The metadata in a perfmap is of lower quality than in a jitdump, so we do not recommend using this flag.

Support for further versions of PHP is currently in the works and should be released before the end of 2023.