I just wrote an article about “Troubleshooting ‘Waiting for table metadata lock’ Errors for both MyISAM and InnoDB Tables” and then ran into a new, different metadata locking issue right after I posted it, and so I thought I’d share that too, just in case anyone ever encounters a similar situation.

In this case, mysqld kept crashing on restart, reporting “out of memory” errors:

/opt/app/mysql/product/mysql/bin//mysqld: Out of memory (Needed 840 bytes)
stack_bottom = 7fb4ebaeae58 thread_stack 0x40000
mysqld: /mysql/mysys/my_new.cc:52: int __cxa_pure_virtual():
  Assertion `! "Aborted: pure virtual method called."' failed.
mysqld: /mysql/mysys/my_new.cc:52: int __cxa_pure_virtual():
  Assertion `! "Aborted: pure virtual method called."' failed.
Fatal signal 6 while backtracing

There is a …

I just want to share about a strange behavior of one of our MySQL server yesterday.
This server is a 5.1.50 MySQL server on debian 4.0 (Yes, I know…)

When a “mysqld got signal 6” error occurred yesterday, the MySQL server crashed and didn’t want to restart.
Then, I found these informations in the error log file :

/usr/local/mysql/bin/mysqld: File '*** glibc detected ***
malloc():memory corruption: 0x00002aac2d5ab460 ***' not found (Errcode: 2)
120306 17:19:47 [ERROR] Failed to open log (file '*** glibc detected ***
malloc():memory corruption: 0x00002aac2d5ab460 ***', errno 2)
120306 17:19:47 [ERROR] Could not open log file
120306 17:19:47 [ERROR] Can't init tc log
120306 17:19:47 [ERROR] Aborting

120306 17:19:47 InnoDB: Starting shutdown...
120306 17:19:53 InnoDB: Shutdown completed; log sequence number 55 1061584593
120306 17:19:53 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete

Great, let see …

Recently I ran into major problems using GNU diff. It would crash with "diff: memory exhausted" after only a few minutes trying to process the differences between a couple 4.5GB files. Even a beefy box with 9GB of RAM would run out of it in minutes.

There is a different solution, however, that is not dependent on file sizes. Enter rdiff – rsync's backbone. You can read about it here: http://en.wikipedia.org/wiki/Rsync (search for rdiff).

The upsides of rdiff are:

• with the same 4.5GB files, rdiff only ate about 66MB of RAM and scaled very well. It never crashed to date.
• it is also MUCH faster than diff.
• rdiff itself combines both diff and patch capabilities, so you can create deltas and apply them using the same program

The downsides of rdiff are:

…