On Mon, Aug 13, 2012 at 11:38:02AM +0200, Neal H. Walfield wrote: > The problem has to do with the recycling of stacks. The problem is > that a thread cannot easily free its own stack when it exits. If it > frees its stack, it can't free it's kernel thread and vice versa. To > work around this, the thread does neither. Instead, later threads > reuse the stack and kernel thread. If the stacks had a non-standard, > we would need some additional code to find an appropriately sized > stack or implement a mechanism to clean up exited threads > periodically.
It seems __pthread_create_internal does a bit of the two, i.e. It attempts to "find" a suitable stack by checking the size of the recycled thread, and if the size doesn't fit, it releases it, leaving itself in a state that tells later functions to allocate a new stack. "Fit" here means the stack size is the default. Why not check against the real stack size as stored in the __pthread structure ? In addition, here you only mention the recylcing problem, not the threadvar alignment problem. Or is there no such problem ? -- Richard Braun
