Re: purify: Free memory read. in shutdown_memory_manager

hi stig, you did that code initally.... if you have a chance - please have a quick look... thanx, tc Rasmus Lerdorf wrote: > > but when i purify i get the attached errors (and i don't understand > > enough about the memory manager)... > > > > could please somebody of the bright guys have a look (and point me into > > the "right" direction)???? > > > > the problem has to do with the statement struct that gets ecalloced in > > oci8.c line 606 > > I guess you are talking about this block: > > **** Purify instrumented ./php (pid 28511) **** > FUM: Freeing unallocated memory: > * This is occurring while in: > free [rtlib.o] > shutdown_memory_manager [alloc.c:357] > php3_request_shutdown [main.c:888] > main [main.c:1859] > _start [crt1.o] > * Attempting to free block at 0x2d8db8 already freed. > * This block was allocated from: > malloc [rtlib.o] > _emalloc [alloc.c:129] > _ecalloc [alloc.c:201] > oci8_parse [oci8.c:606] > php3_oci8_parse [oci8.c:1533] > cs_functioncall_post_variable_passing > [control_structures_inline.h:930] > * There have been 1 frees since this block was freed from: > free [rtlib.o] > shutdown_memory_manager [alloc.c:357] > php3_request_shutdown [main.c:888] > main [main.c:1859] > _start [crt1.o] > > What is this saying? That shutdown_memory_manager() has been called twice > and tried to free it both times? Or is it just telling us that > shutdown_memory_manager() was the function to free it the second time? > If the latter, I guess it can't tell us who freed the block the first > time? If that is the case I might suspect that one of those OCI8 > functions are trying to do a realloc() on it which would be bad news. If > it does a realloc() and hands you back a new chunk of memory that is not > under our control I would expect something along those lines. You > wouldn't be able to use the PHP memory manager in that case and would have > to do a straight malloc() and make very sure that you free the block > yourself when you are done with it. > > The PHP memory manager is very simple. It just allocates a chunk of > memory and then hands it out in smaller chunks when requested and > maintains a linked list of these allocated blocks. If someone forgets to > efree() a particular block, then on request shutdown it walks through the > linked list and writes a little note in the error log informing us that > someone didn't efree something and then it frees the entire chunk. It is > an effective safety net which guards against memory leaks. > > -Rasmus -- PHP Development Mailing List http://www.php.net/ To unsubscribe send an empty message to php-dev-unsubscribe@lists.php.net For help: php-dev-help@lists.php.net