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DanaSoft
Wed 21st Jun '06, 12:09pm
We're experiencing a problem where about 10% of our connect requests result in a delay of 3-4 seconds for the connect to occur. Most connects are handled normally; but out of a series of 20 connects about 2 will result in a long delay.

I tested this with a simple script - all it does is a mysql_connect and measures the time the function takes to execute. I print the results and then close and start again.

A sample of the data looks like this:

Total script execution time: 0.50
Total script execution time: 0.50
Total script execution time: 0.50
Total script execution time: 0.50
Total script execution time: 0.50
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 3.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.51
Total script execution time: 0.52
Total script execution time: 0.52
Total script execution time: 0.52
Total script execution time: 3.51
Total script execution time: 3.51
Total script execution time: 0.51
Total script execution time: 0.52
Total script execution time: 4.31
Total script execution time: 0.31
Total script execution time: 0.32

These connects are from a remote client to a server on the same network. I've tried disabling the DNS lookups for a hostname connect (we use IPs anyways), but that had no effect.

The MySQL server is running just fine - averages 50 queries per second (which is low given our other server does twice that and there are no delays at all) - and has a load under 1.

Is there an underlying cause which would contribute to these delays?

DanaSoft
Wed 21st Jun '06, 3:18pm
Little more info.... our Max Used Connections is only 45 out of 750... Pings all report no traffic loss and quick ping times...

I'm not hitting on any MySQL limits that I can tell; I'm just at my wits end to figure out where the delay is coming from.