> On Feb 20, 2017, at 9:51 AM, Stefan Eissing <stefan.eiss...@greenbytes.de> > wrote: > >> >> Am 20.02.2017 um 15:16 schrieb Jim Jagielski <j...@jagunet.com>: >> >> The below got me thinking... >> >> Right now, the pool allocator mutex is only used when, well, >> allocator_alloc() is called, which means that sometimes >> apr_palloc(), for example, can be thread-safeish and sometimes >> not, depending on whether or not the active node has enough >> space. >> >> For 1.6 and later, it might be nice to actually protect the >> adjustment of the active node, et.al. to, if a mutex is present, >> always be thread-safe... that is, always when we "alloc" memory, >> even when/if we do/don't called allocator_alloc(). >> >> Thoughts? > > So, apr_p*alloc() calls would be thread-safe if a mutex is set in > the underlying allocator? Hmm, at what cost? would be my question. >
The cost would be the time spent on a lock on each call to apr_palloc() or anything that *uses* apr_palloc(). The idea being that if the underlying allocator has a mutex, the assumption should be that the pool using that allocator "wants" or "expects" to be thread-safe... It seems an easy way to create thread-safe APR pools, but I could be missing something crucial here. Of course, if the allocator does NOT have a mutex, no change and no cost.
