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ock contention fix added.

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git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@24715 72102866-910b-0410-8b05-ffd578937521
This commit is contained in:
Richard Frith-MacDonald 2007-02-28 06:24:13 +00:00
parent f0e4035dcd
commit 4c6d361454
2 changed files with 56 additions and 11 deletions
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7
ChangeLog
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@ -1,3 +1,10 @@
2007-02-28 Richard Frith-Macdonald <rfm@gnu.org>
* Source/NSObject.m: Update suggested by Larry Campbell to use 32
locks for managing retain counts rather than just one, so reducing
lock contention when there are lots of threads running.
He reports a 50% performance improvement in his program.
2007-02-27 Nicola Pero <nicola.pero@meta-innovation.com>
* GNUmakefile (CVS_MODULE_NAME): Do not set (exports should be

60
Source/NSObject.m
View file

@ -102,12 +102,36 @@ static Class NSConstantStringClass;
@end
/*
* allocationLock is needed when running multi-threaded for retain/release
* to work reliably.
* We also use it for protecting the map table of zombie information.
* allocationLock is needed when running multi-threaded for
* protecting the map table of zombie information and for retain
* count protection (when using a map table ... REFCNT_LOCAL is NO)
*/
static objc_mutex_t allocationLock = NULL;
/*
* Having just one allocationLock for all leads to lock contention
* if there are lots of threads doing lots of retain/release calls.
* To alleviate this, if using REFCNT_LOCAL, instead of a single
* allocationLock for all objects, we divide the object space into
* chunks, each with its own lock. The chunk is selected by shifting
* off the low-order ALIGNBITS of the object's pointer (these bits
* are presumably always zero) and take
* the low-order LOCKBITS of the result to index into a table of locks.
*/
#define LOCKBITS 5
#define LOCKCOUNT (1<<LOCKBITS)
#define LOCKMASK (LOCKCOUNT-1)
#define ALIGNBITS 3
static objc_mutex_t allocationLocks[LOCKCOUNT] = { 0 };
static inline objc_mutex_t GSAllocationLockForObject(id p)
{
unsigned i = ((((unsigned)(uintptr_t)p) >> ALIGNBITS) & LOCKMASK);
return allocationLocks[i];
}
BOOL NSZombieEnabled = NO;
BOOL NSDeallocateZombies = NO;
@ -274,16 +298,18 @@ NSDecrementExtraRefCountWasZero(id anObject)
#if defined(REFCNT_LOCAL)
if (allocationLock != 0)
{
objc_mutex_lock(allocationLock);
objc_mutex_t theLock = GSAllocationLockForObject(anObject);
objc_mutex_lock(theLock);
if (((obj)anObject)[-1].retained == 0)
{
objc_mutex_unlock(allocationLock);
objc_mutex_unlock(theLock);
return YES;
}
else
{
((obj)anObject)[-1].retained--;
objc_mutex_unlock(allocationLock);
objc_mutex_unlock(theLock);
return NO;
}
}
@ -364,7 +390,9 @@ NSExtraRefCount(id anObject)
if (allocationLock != 0)
{
objc_mutex_lock(allocationLock);
objc_mutex_t theLock = GSAllocationLockForObject(anObject);
objc_mutex_lock(theLock);
node = GSIMapNodeForKey(&retain_counts, (GSIMapKey)anObject);
if (node == 0)
{
@ -374,7 +402,7 @@ NSExtraRefCount(id anObject)
{
ret = node->value.uint;
}
objc_mutex_unlock(allocationLock);
objc_mutex_unlock(theLock);
}
else
{
@ -408,15 +436,17 @@ NSIncrementExtraRefCount(id anObject)
#if defined(REFCNT_LOCAL)
if (allocationLock != 0)
{
objc_mutex_lock(allocationLock);
objc_mutex_t theLock = GSAllocationLockForObject(anObject);
objc_mutex_lock(theLock);
if (((obj)anObject)[-1].retained == UINT_MAX - 1)
{
objc_mutex_unlock (allocationLock);
objc_mutex_unlock (theLock);
[NSException raise: NSInternalInconsistencyException
format: @"NSIncrementExtraRefCount() asked to increment too far"];
}
((obj)anObject)[-1].retained++;
objc_mutex_unlock (allocationLock);
objc_mutex_unlock (theLock);
}
else
{
@ -868,6 +898,14 @@ GSDescriptionForClassMethod(pcl self, SEL aSel)
{
if (allocationLock == 0)
{
#if defined(REFCNT_LOCAL)
unsigned i;
for (i = 0; i < LOCKCOUNT; i++)
{
allocationLocks[i] = objc_mutex_allocate();
}
#endif
allocationLock = objc_mutex_allocate();
}
}