Master freezes with clogged connections, zero load (1 reply)

Hello,

A very strange problem has ocurred to our replication setup recently. Our setup has one Master and four Slaves and ran well for several years. We're currently using MySQL version 5.5.47.0+debian7u1.

After we've recently performed some upgrades in regards to glibc where quite some other packages were upgraded too (but not MySQL), our Master began to run into a freeze after a few days. The sympom being that all MySQL connections (255) were clogged, but were simplay not being executed. The load was zero, there were no error message anywhere. MySQL basically just halted working. So we had to kill MySQL, restart it, and fiddle with setting up a new and consistent replication. Later we switched the machine to a backup system with identical hardware, but after a few days this new system ran into a freeze again.

Now we intend to switch to a completely new hardware setup with a different controller, processor and so on, but this is basically just a vague guess.

Strangely, if we configure such a "sick master" as a Slave, it will not freeze. This only happens to our masteres since the distro package upgrades.

Any ideas on what could cause a Master to just hang without an error?

THank you very much for any advice!

Regards