On 17 July 2014 at 18:00, <stef...@apache.org> wrote: > Author: stefan2 > Date: Thu Jul 17 15:00:33 2014 > New Revision: 1611380 > > URL: http://svn.apache.org/r1611380 > Log: > Work around for the poor performance of APR reader / writer locks on Windows. > Basically, fall back to 1.7 code on Win32 by using a simple mutex. > > This resulted in a 35% increase in throughput for a 'null-export' over > ra_serf from hot SVN caches with revprop caching enabled. OTOH, this may > cost us some scalability with ra_svn on high-speed (>1Gb) networks. > > * subversion/libsvn_subr/cache-membuffer.c > (USE_SIMPLE_MUTEX): New flag. Set depending on whether we need to fall > back to a simple locking scheme. > (svn_membuffer_t): Select lock type at compile time. > (read_lock_cache, > write_lock_cache, > force_write_lock_cache, > unlock_cache): Use the simple mutex lock when selected. > (svn_cache__membuffer_cache_create): Initialize the correct lock type and > disable the counter_mutex if redundant. > > Modified: > subversion/trunk/subversion/libsvn_subr/cache-membuffer.c > [...] > @@ -674,6 +712,12 @@ static svn_error_t * > unlock_cache(svn_membuffer_t *cache, svn_error_t *err) > { > #if APR_HAS_THREADS > +# if USE_SIMPLE_MUTEX > + > + return svn_mutex__unlock(cache->lock, SVN_NO_ERROR); > + > +# else > + > if (cache->lock) > { > apr_status_t status = apr_thread_rwlock_unlock(cache->lock); > @@ -683,6 +727,8 @@ unlock_cache(svn_membuffer_t *cache, svn > if (status) > return svn_error_wrap_apr(status, _("Can't unlock cache mutex")); > } > + > +# endif > #endif > return err; > } The provided ERR argument is ignored in USE_SIMPLE_MUTEX codepath. So any error from cache serializer will be ignored and invalid result will be used.
-- Ivan Zhakov
