Am Donnerstag, 1. Mai 2014, 06:37:04 schrieb Jim Jagielski: > I would really appreciate subversion's input on this... > in many many ways, they push APR to its limits, esp > related to pools.
I don't know if subversion uses threads heavily. I suspect that the pattern of pools being used by different worker threads is unique to mpm_event. > Is there anyway this trylock could be conditional? > For example, could we add some sort of flag or whatever > that would implement this on specifically created pools? We could do that, but I don't really see a use case. I was imagining a debug option that is globally switchted on by a configure option. And this would not be used in production, at least not unless one is hunting a specific bug. What use did you have in mind? Maybe you were looking for some really thread-safe pools that use a mutex to serialize accesses? In this case, the mutex would be enabled by some flag to apr_pool_create(). There is PR 51392 requesting that. If you think that would be useful, that could be something for apr 1.6. > On May 1, 2014, at 5:16 AM, Stefan Fritsch <s...@sfritsch.de> wrote: > > Hi, > > > > it's currently rather hard to debug issues caused by pools being > > used by different threads. The current pool debugging options > > don't really work if pool ownership changes during runtime (as > > int mpm event), require specific apr_pool_owner_set() calls, and > > apr compiled with pool debugging is significantly slower than > > normal apr. > > > > So, I had the following idea for a lightweight debugging help: > > > > All pool operations are protected by mutexes. But in order to get > > the mutex, the operations use apr_thread_mutex_trylock(). If > > there is any contention while getting the mutex, we abort(). This > > would only catch threading issues during relatively high load > > when there is actual contention. But the mutex operations should > > be relatively cheap comparted to the full blown pool debugging. > > So maybe this feature could be even enabled by default if > > compiled in maintainer mode. > > > > Do you think this would be a good idea? > > > > Cheers, > > Stefan
