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Displaying posts with tag: stack (reset)
Caring about stack usage

It may not be surprising that there’s been a few projects over the years that I’ve worked on where we’ve had to care about stack usage (to varying degrees).

For threaded userspace applications (e.g. MySQL, Drizzle) you get a certain amount of stack per thread – and you really don’t want to bust that. For a great many years now, there’s been both a configuration parameter in MySQL to set how much stack each thread (connection) gets as well as various checks in the source code to ensure there’s enough free stack to do a particular operation (IIRC open_table is the most hairy one of this in MySQL).

For the Linux Kernel, stack usage is a relatively (in)famous problem… although by now just about every real problem has been fixed and merely mentioning it is probably just the influence of the odd grey beard hairs I’m pretending not to notice.

In a current project I’m working on, it’s also something we have …

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Limiting functions to 32k stack in Drizzle (and scoped_ptr)

I wonder if this comes under “Code Style” or not…

Anyway, Monty and I finished getting Drizzle ready for adding “-Wframe-larger-than=32768″ as a standard compiler flag. This means that no function within the Drizzle source tree can use greater than 32kb stack – it’s a compiler warning – and with -Werror, it means that it’s a build error.

GCC is not perfect at detecting stack usage, but it’s pretty good.

Why have we done this?

Well, there is a little bit of recursion in the server… and we can craft queries to blow a small stack (not so good). On MacOS X, the default thread stack size is only 512kb. This gives not many frames if 32kb stack is a even remotely common.

I found some interesting places to throw a lot of things on the stack too – that would be rather far down on a …

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The Rise of The Open Source Software Stack

The rise of the "Open Source Software Stack" reached another milestone today.  

Sun released a SPECjAppServer2004 performance result using top-to-bottom Open Source Software stack components:  OpenSolaris/MySQL/Glassfish.   At 1197.10 JOPS, the performance is highly respectable - not setting any land speed records, but it is in the ball park with other results using the same class of hardware.   The difference (of course) is in the price/performance.

The other contenders were two [1][ …

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