#2087: On a PPC Mac OS X 10.4, the RTS reports "Memory leak detected" running a
program compiled with -debug -threaded -fhpc
----------------------------+-----------------------------------------------
Reporter: thorkilnaur | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.8.3
Component: Runtime System | Version: 6.9
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: powerpc
Os: MacOS X |
----------------------------+-----------------------------------------------
Comment (by thorkilnaur):
Additional investigation strongly indicates that the uncounted blocks are
the ones allocated by {{{hs_add_root}}} in {{{RtsStartup.c}}}:
{{{
void
hs_add_root(void (*init_root)(void))
{
bdescr *bd;
nat init_sp;
Capability *cap = &MainCapability;
if (hs_init_count <= 0) {
barf("hs_add_root() must be called after hs_init()");
}
/* The initialisation stack grows downward, with sp pointing
to the last occupied word */
init_sp = INIT_STACK_BLOCKS*BLOCK_SIZE_W;
bd = allocGroup_lock(INIT_STACK_BLOCKS);
init_stack = (F_ *)bd->start;
init_stack[--init_sp] = (F_)stg_init_finish;
if (init_root != NULL) {
init_stack[--init_sp] = (F_)init_root;
}
cap->r.rSp = (P_)(init_stack + init_sp);
StgRun((StgFunPtr)stg_init, &cap->r);
freeGroup_lock(bd);
startupHpc();
// This must be done after module initialisation.
// ToDo: make this work in the presence of multiple hs_add_root()s.
initProfiling2();
}
}}}
The memory leak is reported when a garbage collection happens to be
initiated before the blocks are freed again. This can be confirmed by
inserting a call to memInventory between the allocation and the free: Such
a call reports the memory leak every time.
So it is not actually a real memory leak, merely a weakness in the memory
leak detector.
I will gladly concoct a repair of this problem, but the possibilities are
many, so I will just hesitate for a little while and see if not somebody
else might come up with just the right solution.
Thanks and best regards Thorkil
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2087#comment:4>
GHC <http://www.haskell.org/ghc/>
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