[bug] apcu_fetch block while on busy server

[cash2910]

apcu

APCu Support => Enabled
Version => 5.1.14
APCu Debugging => Disabled
MMAP Support => Enabled
MMAP File Mask =>
Serialization Support => php, igbinary
Build Date => Dec 5 2018 15:59:57

Directive => Local Value => Master Value
apc.coredump_unmap => Off => Off
apc.enable_cli => Off => Off
apc.enabled => On => On
apc.entries_hint => 4096 => 4096
apc.gc_ttl => 3600 => 3600
apc.mmap_file_mask => no value => no value
apc.preload_path => no value => no value
apc.serializer => default => default
apc.shm_segments => 1 => 1
apc.shm_size => 4G => 4G
apc.slam_defense => Off => Off
apc.smart => 0 => 0
apc.ttl => 0 => 0
apc.use_request_time => On => On

It works fine on my development enverments , bug when I run it in production enverments that serves a lot of requests per second . It blocks all the php-fpm processes after work some day . I hava to restart the php-fpm to slove this problem .
I have turn up the apc.shm_size to 4G . but yesterday I got the same problem when it at 1G ,

please help me . many thanks ....

[nikic]

Could you check if setting apc.serializer=php resolves this problem?

[nikic]

Also released new version that switches the default of apc.serializer and has a few other fixes.

[cash2910]

Tks , I will try it . but why it causes this problem .