Re: browscap and nesting level too deep (bug #25916)

One solution (attached is the patch, if nobody has someone against it I will apply it): I switch off the recursion protection for the browscap hash in zend_hash_init_ex because this hash has no recursive things in it and is not modified after it is created. Uwe At 18:06 03.12.2003, Uwe Schindler wrote: >Today I got the error from bug #25916 several times on our webserver. >Looking through the code I found out the following: >* It depends NOT on the fact if there is a parameter to get_browser() or not >* It happens sometimes when server is very heavy loaded, the homepage of >the domain uses the get_browser() function and is the most visited page. > >So it must be a multithreading issue (NSAPI is a multithreading >webserver). And I have an idea: >Line 257 uses: > zend_hash_apply_with_arguments(&browser_hash, (apply_func_args_t) > browser_reg_compare, 2, lookup_browser_name, &found_browser_entry); > >This is the only function in this context in zend_hash.c which uses the >Recursion protection with >#define HASH_PROTECT_RECURSION(ht) \ > if ((ht)->bApplyProtection) { \ > if ((ht)->nApplyCount++ >= 3) { \ > zend_error(E_ERROR, "Nesting level too deep - > recursive dependency?"); \ > } \ > } > >The browser hashtable is a global variable in browscap.c and can be used >by more than one call to get_browser() even at the same time. So if one >zend_hash_apply_with_arguments() locks the hashtable and a second and >third thread tries to do that you will get the error, because >(ht)->nApplyCount++ raises and raises... > >This evening I will try to put a mutex at the beginning of get_browser to >prevent more threads running at the same time there. But as I see this, >this zend_hash_apply function is used very often could there be other >effects if a global variable is a hashtable? > >Only one question: Is there a special PHP way to use mutexes? I am not >familar in Zend programming (I do only SAPI...) ----- Uwe Schindler thetaphi@php.net - http://www.php.net NSAPI SAPI developer Erlangen, Germany

Index: ext/standard/browscap.c =================================================================== RCS file: /repository/php-src/ext/standard/browscap.c,v retrieving revision 1.60.2.15 diff -u -r1.60.2.15 browscap.c --- ext/standard/browscap.c 13 Aug 2003 23:39:03 -0000 1.60.2.15 +++ ext/standard/browscap.c 3 Dec 2003 17:15:01 -0000 @@ -149,7 +149,7 @@ zend_file_handle fh; memset(&fh, 0, sizeof(fh)); - if (zend_hash_init(&browser_hash, 0, NULL, (dtor_func_t) browscap_entry_dtor, 1)==FAILURE) { + if (zend_hash_init_ex(&browser_hash, 0, NULL, (dtor_func_t) browscap_entry_dtor, 1, 0)==FAILURE) { return FAILURE; }