php / php/php-src

JIT cause 100% cpu usage

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Bug Category: JIT Status: Needs Triage
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Description

Description

The following code:

    [opcache]
    opcache.enable=1
    opcache.enable_cli=1
    opcache.memory_consumption=512
    opcache.jit_buffer_size=256M
    opcache.interned_strings_buffer=16
    opcache.max_accelerated_files=200000
    opcache.max_wasted_percentage=5
    opcache.use_cwd=1
    opcache.validate_timestamps=0
    opcache.revalidate_freq=600
    opcache.revalidate_path=0
    opcache.save_comments=1
    opcache.enable_file_override=0
    opcache.optimization_level=0x7FFFBFFF
    opcache.dups_fix=0
    opcache.max_file_size=0
    opcache.consistency_checks=0
    opcache.force_restart_timeout=180
    opcache.file_cache_only=0
    opcache.file_cache_consistency_checks=1
    opcache.huge_code_pages=1
    opcache.preload=/path/to/config/preload.php
    opcache.preload_user=user

Resulted in this output:

[18-Jul-2023 03:40:09] NOTICE: [pool www] child 179 started
Fatal error: Maximum execution time of 99+2 seconds exceeded (terminated) in /path/to/file.php on line 33
[18-Jul-2023 03:40:13] WARNING: [pool www] child 47 exited with code 124 after 381.082060 seconds from start
[18-Jul-2023 03:40:13] NOTICE: [pool www] child 182 started
Fatal error: Maximum execution time of 99+2 seconds exceeded (terminated) in /path/to/file.php on line 33
[18-Jul-2023 03:40:25] WARNING: [pool www] child 42 exited with code 124 after 393.292804 seconds from start

But I expected this output instead:

no errors in log

Hello,
after enabling JIT, our application start perform better (~10% faster). But, some php-fpm pods (~1 in 20) after start use all available cpu and timeout the requests. After pod restart, everything back to normal. Without JIT everything is ok and cpu utilization is at normal value.

Regards

opcache.blacklist_filename => no value => no value
opcache.consistency_checks => 0 => 0
opcache.dups_fix => Off => Off
opcache.enable => On => On
opcache.enable_cli => On => On
opcache.enable_file_override => Off => Off
opcache.error_log => no value => no value
opcache.file_cache => no value => no value
opcache.file_cache_consistency_checks => On => On
opcache.file_cache_only => Off => Off
opcache.file_update_protection => 2 => 2
opcache.force_restart_timeout => 180 => 180
opcache.huge_code_pages => On => On
opcache.interned_strings_buffer => 16 => 16
opcache.jit => tracing => tracing
opcache.jit_bisect_limit => 0 => 0
opcache.jit_blacklist_root_trace => 16 => 16
opcache.jit_blacklist_side_trace => 8 => 8
opcache.jit_buffer_size => 256M => 256M
opcache.jit_debug => 0 => 0
opcache.jit_hot_func => 127 => 127
opcache.jit_hot_loop => 64 => 64
opcache.jit_hot_return => 8 => 8
opcache.jit_hot_side_exit => 8 => 8
opcache.jit_max_exit_counters => 8192 => 8192
opcache.jit_max_loop_unrolls => 8 => 8
opcache.jit_max_polymorphic_calls => 2 => 2
opcache.jit_max_recursive_calls => 2 => 2
opcache.jit_max_recursive_returns => 2 => 2
opcache.jit_max_root_traces => 1024 => 1024
opcache.jit_max_side_traces => 128 => 128
opcache.jit_prof_threshold => 0.005 => 0.005
opcache.lockfile_path => /tmp => /tmp
opcache.log_verbosity_level => 1 => 1
opcache.max_accelerated_files => 200000 => 200000
opcache.max_file_size => 0 => 0
opcache.max_wasted_percentage => 5 => 5
opcache.memory_consumption => 512 => 512
opcache.opt_debug_level => 0 => 0
opcache.optimization_level => 0x7FFFBFFF => 0x7FFFBFFF
opcache.preferred_memory_model => no value => no value
opcache.preload => /path/to/config/preload.php => //path/to/config/preload.php
opcache.preload_user => user => user
opcache.protect_memory => Off => Off
opcache.record_warnings => Off => Off
opcache.restrict_api => no value => no value
opcache.revalidate_freq => 600 => 600
opcache.revalidate_path => Off => Off
opcache.save_comments => On => On
opcache.use_cwd => On => On
opcache.validate_permission => Off => Off
opcache.validate_root => Off => Off
opcache.validate_timestamps => Off => Off
PHP Version

PHP 8.1.20

Operating System

Debian GNU/Linux 10 (buster) docker container on Amazon Linux 2

Contributor guide

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No source file, test, or minimal reproducer is mentioned. Start by reproducing the PHP 8.1.20 behavior with the supplied OPcache/JIT configuration on the Debian container, comparing JIT enabled and disabled; done means identifying a reproducible trigger and verifying a fix or documented limitation.

Written by the indexing model from the issue text.

Assessment

Tech stack
php
Domain
compilers, performance
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
20/100

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