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This article focuses on "how to solve the Warning: a long semaphore wai problem of InnoDB". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to solve the Warning: a long semaphore wai problem of InnoDB.

InnoDB: Warning: a long semaphore wait:-- Thread 47843012708096 has waited at btr/btr0cur.c line 467 for 334.00 seconds the semaphore:

The original linux kernel semaphore default setting is too small, pressure testing, resulting in a lot of waiting

Default

# cat / proc/sys/kernel/sem

250 32000 32 128

Description:

The first column represents the maximum number of semaphores in each signal set.

The second column represents the total number of system-wide maximum semaphores.

The third column represents the maximum number of system operations when each signal occurs.

The fourth column represents the system-wide maximum total number of signal sets.

Adjust the third column a little larger to refer to the data on the network

Echo "kernel.sem=250 32000 100128" > > / etc/sysctl.conf

Then sysctl-p

Restart mysql

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