Re: Request-global hashtable initialization

On Thursday, 12 April 2018 22:34:52 CEST Nikita Popov wrote: > On Thu, Apr 12, 2018 at 9:53 PM, Heinz Wiesinger <HMWiesinger@liwjatan.at> > > wrote: > > Hi everyone! > > > > I ventured into writing my first PHP extension and did pretty well so far > > following the existing documentation and example code inside the php > > source. > > > > However, I hit an odd bug in my code that I can't quite explain. I'm > > obviously > > missing something and I hope someone here can point me in the right > > direction > > > > :) > > > > I'd like to set up a request global hashtable. For now I'm running > > ALLOC_HASHTABLE() and zend_hash_init() inside PHP_GINIT_FUNCTION. I then > > have > > a user function that's supposed to add entries to that hashtable and > > another > > user function that reads entries from the hashtable. > > > > I tested with code passed directly on the command line (using php -r) and > > that > > works just like I would expect it too. The value gets written to the > > hashtable > > and I can read it afterwards from the other function. I also verified it's > > the > > same value that I first stored, so from what I can tell the basic > > functionality is good. > > > > When I take the same testcode and write it into a file, and then run php > > on > > that file, execution aborts trying to allocate almost 2GB of memory when > > trying to store the value in the hashtable (using zend_hash_update()). I > > can > > see PHP_GINIT_FUNCTION being executed in that case as well so I'd assume > > the > > hashtable is setup just fine. Yet something is different. > > > > What's the difference between " php -r '' " and "php > > test.php" in that > > regard? > > > > I uploaded my current state of the extension to github in case someone > > would > > like to take a closer look at the code: > > https://github.com/pprkut/ > > autoload-psr > > > > Thanks in advance! > > > > Grs, > > Heinz > > > https://github.com/pprkut/autoload-psr/blob/27cfc53c864116cf0b65b8f7e69464e1 > 5b3fdef5/autoload_psr.c#L175 should be using ZVAL_STR_COPY. The hashtable > API does not automatically incref stored values. > > I'd suggest running under USE_ZEND_ALLOC=0 valgrind to check for further > memory issues. Differences in the mode of execution are likely just > incidental. Thanks for the pointers! I tried running it under valgrind, but couldn't find anything. So I tried without valgrind, but with USE_ZEND_ALLOC=0 and found that I can't reproduce the problem like that. Looks to me that something I do doesn't play well with the zend allocator. Incidentally valgrind also doesn't tell me about the issue with ZVAL_STR that you pointed out. Maybe I'm using it wrong? I tried USE_ZEND_ALLOC=0 valgrind --tool=memcheck --leak-check=full php - dextension=modules/autoload_psr.so test2.php Grs, Heinz

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