Symptoms
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Websites or webmail can't be reached.
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Plesk is not accessible:
Gateway error 502
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The following entry can be found in
/var/log/httpd/error_log:Fatal Error Unable to allocate shared memory segment of 134217728 bytes: mmap: Cannot allocate memory (12)
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topcommand shows enough RAM on the server, more than was mentioned in the error entry above; -
sw-engine service cannot start:
# service sw-engine start
Starting sw-engine-fpm: Fri Aug 17 20:40:58 2018 (11150): Fatal Error Unable to allocate shared memory segment of 134217728 bytes: mmap: Cannot allocate memory (12) -
Container limits checking shows the following:
# cat /proc/user_beancounters | grep shm
shmpages 17604 17604 20480 20480 18
Cause
Container limit shmpages is exceeded by OPcache, which needs more, than segments available.
Resolution
Change OPcache limit
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Connect to the server via SSH.
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Check current segment size:
# ipcs -lm
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 32768
max total shared memory (kbytes) = 8388608
min seg size (bytes) = 1 -
Go to Tools & Settings > PHP Settings > <PHP version, that has many domains> > php.ini.
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Uncomment
opcache.memory_consumptionoption and set it equal to the segment limit (In this case 32) - changes applied automatically to all the domains, that are using this PHP version.
Increase number of segments
Note: If you have access to the Hardware Node, use the resolution below. If not, contact your provider to increase the limit for you.
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1.Connect to the server via SSH.
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Increase the amount of the corresponding UBC limit for the container to at least 40960:
# vzctl set 10001 --shmpages 40960 --save
with