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Tag Archives: gdb
Read ahead…
Mark wrote about how to find situations where InnoDB read-ahead is a bottleneck. What he didn’t disclose, though, is his trick to disable read-ahead without restart or recompile of MySQL. See, there’s no internal “disable read ahead knob”. But there … Continue reading
When bad things happen!
When bad things happen, like… ‘strace -f’ or ‘gdb’ or any other process inspection tool decides to hang your precious processes (they show up in state T in process lists), there’s always help: #include <sys/ptrace.h> #include <signal.h> main(int ac, char … Continue reading
GDB 7!
I wasn’t prepared for this. After spending months playing with GDB development trees I somehow entirely missed that 7.0 release is getting close, and took me more than an hour to spot it. My favorite features are python scripting and … Continue reading
Evil replication management
When one wants to script automated replication chain building, certain things are quite annoying, like immutable replication configuration variables. For example, at certain moments log_slave_updates is more than needed, and thats what the server says: mysql> show variables like ‘log_slave_updates’; … Continue reading
On binaries and -fomit-frame-pointer
Over last few years 64-bit x86 platform has became ubiquitous, thus making stupid memory limitations a thing of some forgotten past. 64-bit processors made internal memory structures bigger, but compensated that with twice the amount and twice larger registers. But … Continue reading
Checksums again, some I/O too
When I was doing data loading tests, I realized that usually low checksum calculation CPU percentage is actually the blocking factor. See, usually when background writers do the flushing, it gets parallelized, but if active query is forcing a checkpoint, … Continue reading
Poor man’s contention profiling
I wrote already about poor man’s query profiling techniques last summer. Today I’m going to share poor man’s contention profiling tool, for all these poor souls which do not have Solaris with dtrace or pstack, don’t want to run tcmalloc … Continue reading