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Displaying posts with tag: ulimit (reset)

MySQL file limit, table cache and max_connections
+1 Vote Up -0Vote Down

MySQL variables open_files_limit, table_open_cache and max_connections are
inter-related, and this is for obvious reasons: all deal with file descriptors
one way or another.

If one of the value is provided but others are left out, mysqld calculates
others using a formula and in some cases, emits a warning if not possible.

The whole calculation behind obtaining the final file descriptor limit is a bit
byzantine and is as follows (for Linux):

EDIT: This applies to MySQL 5.5, in 5.6, as Daniël in comments pointed out,
few things have changed, check comment for details. I will probably make a





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Changing process.max-file-descriptor using 'ulimit -n' can cause MySQL to change table_open_cache value
Employee +0 Vote Up -0Vote Down

Before I get into details here is the bottom line. If you start MySQL on Solaris as a non-root (ie, mysql) user and for some reason you need to adjust the file descriptor resource limit for the parent shell, never use 'ulimit -n'. This will set both the soft and hard limit and may cause MySQL to adjust the max_connections and table_open_cache configuration variables upon next startup.

Use either:

 ulimit -S -n 1024

or something like:

  prctl -n process.max-file-descriptor -t basic -v  1024 -r -i process $$



The Details

The default 'basic' privilege value for the resource control process.max-file-descriptor is 256. This control represents the soft ulimit for file descriptors per process. The default 'privileged' privilege is set to 65535, which represents the hard ulimit. A non-root



  [Read more...]
Changing process.max-file-descriptor using 'ulimit -n' can cause MySQL to change table_open_cache value
Employee +0 Vote Up -0Vote Down

Before I get into details here is the bottom line. If you start MySQL on Solaris as a non-root (ie, mysql) user and for some reason you need to adjust the file descriptor resource limit for the parent shell, never use 'ulimit -n'. This will set both the soft and hard limit and may cause MySQL to adjust the max_connections and table_open_cache configuration variables upon next startup.

Use either:

 ulimit -S -n 1024

or something like:

  prctl -n process.max-file-descriptor -t basic -v  1024 -r -i process $$



The Details

The default 'basic' privilege value for the resource control process.max-file-descriptor is 256. This control represents the soft ulimit for file descriptors per process. The default 'privileged' privilege is set to 65535, which represents the hard ulimit. A



  [Read more...]
Changing process.max-file-descriptor using 'ulimit -n' can cause MySQL to change table_open_cache value
Employee +0 Vote Up -0Vote Down

Before I get into details here is the bottom line. If you start MySQL on Solaris as a non-root (ie, mysql) user and for some reason you need to adjust the file descriptor resource limit for the parent shell, never use 'ulimit -n'. This will set both the soft and hard limit and may cause MySQL to adjust the max_connections and table_open_cache configuration variables upon next startup.

Use either:

 ulimit -S -n 1024

or something like:

  prctl -n process.max-file-descriptor -t basic -v  1024 -r -i process $$



The Details

The default 'basic' privilege value for the resource control process.max-file-descriptor is 256. This control represents the soft ulimit for file descriptors per process. The default 'privileged' privilege is set to 65535, which represents the hard ulimit. A



  [Read more...]
Showing entries 1 to 4

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