Re: GMP memory allocator, various issues

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Le 11/10/2014 02:24, Rasmus Lerdorf a écrit : > On 10/10/2014 09:50 AM, Stas Malyshev wrote: >> Hi! >> >>> Can you please elaborate a little ? Doesn't such leak have to >>> be fixed in ext/gmp ? >> >> We clean up the memory at the end of the request. But if the >> request ended abnormally and we had some active gmp objects, with >> gmp data allocated outside emalloc we could not clean that and it >> ends up being persistent memory leak. Also, of course, that also >> excepts gmp objects from PHP memory limit, which makes it less >> useful. > > At the same time we can't just switch libgmp to our allocator in > MINIT since it gets called by other libraries outside of a PHP > request as Remi pointed out via Apache's mod_gnutls. And also from > within a PHP request but indirectly via freetds+gnutls where > freetds has no idea we have switched the allocator on them. > > We need to make it more granular. gmp_init() should set it and set > a flag and then in RSHUTDOWN we can check that flag and restore > the default allocator to take care of the outside-request access, > and for inside-request access like the freetds extension, we > probably need to explicitly set it back to the default handler in > that extension in each call that might call it. Huge PITA to catch > all those cases though. We cannot, as we are not always aware of it (in case of odbc => freetds => gnutls) I think the only place we are aware of the need of our allocator is in our gmp extension, which means - - beginning of each gmp* function - save current allocators => mp_get_memory_functions - set ours => mp_set_memory_functions - - end of end function - restore allocators => mp_set_memory_functions Yes, and probably lower perfs (but perhaps not significantly) I will try to create a patch, for test, as we really need to fix this problem, especially it gmp going to go into core (bigint patch). Remi. > > -Rasmus > -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlQ4whQACgkQYUppBSnxahiOPQCgwqFgYYTFp1sTFHyd0zaZuYwg yqQAoMY3fAghfHjk+OFMabTIyuv1oiGF =vH1h -----END PGP SIGNATURE-----