A more efficient atomicModifyIORef'
atomicModifyIORef'
is currently defined as:
atomicModifyIORef' ref f = do
b <- atomicModifyIORef ref
(\x -> let (a, b) = f x
in (a, a `seq` b))
b `seq` return b
This doesn't seem to be the best we can do, though.
The following implementation exhibits a speedup of 1.7x (vanilla RTS) / 1.4x (threaded RTS) over the current implementation:
atomicModifyIORef' ref f = do
b <- atomicModifyIORef ref $ \a ->
case f a of
v@(a',_) -> a' `seq` v
b `seq` return b
The differences between this version and the current version are:
- the lambda is now strict in
f a
, and - a new result tuple is no longer being allocated.
Is there a good reason why atomicModifyIORef'
is not already defined this way?
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.3 |
Type | Task |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | libraries/base |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | joeyadams |
Operating system | |
Architecture |