If you compile your own MySQL server on FreeBSD and link with the LinuxThreads library, make sure to compile with the -DHAVE_BROKEN_REALPATH option.

The short version is that FreeBSD's realpath() isn't thread-safe. That causes badness with LinuxThreads on FreeBSD, because MySQL uses lots of relative paths and globally shared file descriptors may end up pointing to all the wrong places. I'll explain in more detail if I get a chance.

Oh, you could just read my post to the MySQL Internals mailing list, too, I guess. Heh. Sorry I can't link to the original. The web archives are a little funky. Hmm.

Posted by jzawodn at October 21, 2002 11:18 PM

Reader Comments
# Aziz Khawaja said:

/- in memory queue
Data source ----TCP/IP-ŕ thread -- in memory - - thread / - in memory queue - - - - TCP/IP - - > another
Queue … in memory queue process

Data comes in IP to a thread.
That thread processes the data and places it in an in-memory inter-process queue
Another thread picks it up out of that queue and routes it to one of 8 other in-memory inter-process queues.
8 other threads are running (on for each of the queues) that pulls out of their queue and sends the data to another process

The problem:
When the system is configured to run on a ONE CPU machine, the system throughput is roughly 74,000 msg/second. When the system is configured to run on a 2 CPU machine, the system throughput is roughly 27,000 msg/second.

The data source and ‘another process’ are running on different machines and they are consuming very little CPU. They have be ruled out as having any type of a performance problem so the data is available for the main application to consume.

We had the same issue when running the application on a multiple CPU Solaris box. We added the following VM arg: -XX:-UseLWPSynchronization
And added /usr/lib/lwp to the LD_LIBRARY_PATH environment variable. The throughput of the system increase 2 to 3 times when these options were used.

Please help!

on June 19, 2003 07:17 AM
# Pritesh Gupta said:

Hi i have created my database named "ibdata1" using Mysql When i connect it connects successfully but after when i write the right code , then it shows
ERROR 1049 (42000): unknown database "ibdata1"
plz reply ASAP

Thanks and regards
Pritesh Gupta

on April 28, 2008 10:34 AM
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