X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2Fsm%2FMarkWeak.c;h=4f0a7a451ba30dd4383dbb3287361dc137a602a9;hb=a2a67cd520b9841114d69a87a423dabcb3b4368e;hp=5f71a30627e9553b49515285e3f2135ac2fdf36d;hpb=e7987f16175f88daa11f06f25d10161a95f84bc4;p=ghc-hetmet.git diff --git a/rts/sm/MarkWeak.c b/rts/sm/MarkWeak.c index 5f71a30..4f0a7a4 100644 --- a/rts/sm/MarkWeak.c +++ b/rts/sm/MarkWeak.c @@ -11,14 +11,16 @@ * * ---------------------------------------------------------------------------*/ +#include "PosixSource.h" #include "Rts.h" -#include "Storage.h" + #include "MarkWeak.h" #include "GC.h" #include "GCThread.h" #include "Evac.h" #include "Trace.h" #include "Schedule.h" +#include "Weak.h" /* ----------------------------------------------------------------------------- Weak Pointers @@ -96,6 +98,7 @@ traverseWeakPtrList(void) StgWeak *w, **last_w, *next_w; StgClosure *new; rtsBool flag = rtsFalse; + const StgInfoTable *info; switch (weak_stage) { @@ -120,12 +123,14 @@ traverseWeakPtrList(void) continue; } - switch (get_itbl(w)->type) { - - case EVACUATED: - next_w = (StgWeak *)((StgEvacuated *)w)->evacuee; + info = w->header.info; + if (IS_FORWARDING_PTR(info)) { + next_w = (StgWeak *)UN_FORWARDING_PTR(info); *last_w = next_w; continue; + } + + switch (INFO_PTR_TO_STRUCT(info)->type) { case WEAK: /* Now, check whether the key is reachable. @@ -202,55 +207,58 @@ traverseWeakPtrList(void) } ASSERT(get_itbl(t)->type == TSO); - switch (t->what_next) { - case ThreadRelocated: + if (t->what_next == ThreadRelocated) { next = t->_link; *prev = next; continue; - case ThreadKilled: - case ThreadComplete: - // finshed or died. The thread might still - // be alive, but we don't keep it on the - // all_threads list. Don't forget to - // stub out its global_link field. - next = t->global_link; - t->global_link = END_TSO_QUEUE; + } + + next = t->global_link; + + // This is a good place to check for blocked + // exceptions. It might be the case that a thread is + // blocked on delivering an exception to a thread that + // is also blocked - we try to ensure that this + // doesn't happen in throwTo(), but it's too hard (or + // impossible) to close all the race holes, so we + // accept that some might get through and deal with + // them here. A GC will always happen at some point, + // even if the system is otherwise deadlocked. + // + // If an unreachable thread has blocked + // exceptions, we really want to perform the + // blocked exceptions rather than throwing + // BlockedIndefinitely exceptions. This is the + // only place we can discover such threads. + // The target thread might even be + // ThreadFinished or ThreadKilled. Bugs here + // will only be seen when running on a + // multiprocessor. + if (t->blocked_exceptions != END_TSO_QUEUE) { + if (tmp == NULL) { + evacuate((StgClosure **)&t); + flag = rtsTrue; + } + t->global_link = exception_threads; + exception_threads = t; *prev = next; continue; - default: - ; } - + if (tmp == NULL) { // not alive (yet): leave this thread on the // old_all_threads list. prev = &(t->global_link); - next = t->global_link; } else { // alive - next = t->global_link; *prev = next; - // This is a good place to check for blocked - // exceptions. It might be the case that a thread is - // blocked on delivering an exception to a thread that - // is also blocked - we try to ensure that this - // doesn't happen in throwTo(), but it's too hard (or - // impossible) to close all the race holes, so we - // accept that some might get through and deal with - // them here. A GC will always happen at some point, - // even if the system is otherwise deadlocked. - if (t->blocked_exceptions != END_TSO_QUEUE) { - t->global_link = exception_threads; - exception_threads = t; - } else { - // move this thread onto the correct threads list. - step *new_step; - new_step = Bdescr((P_)t)->step; - t->global_link = new_step->threads; - new_step->threads = t; - } + // move this thread onto the correct threads list. + step *new_step; + new_step = Bdescr((P_)t)->step; + t->global_link = new_step->threads; + new_step->threads = t; } } } @@ -274,10 +282,21 @@ traverseWeakPtrList(void) for (t = stp->old_threads; t != END_TSO_QUEUE; t = next) { next = t->global_link; - tmp = t; - evacuate((StgClosure **)&tmp); - tmp->global_link = resurrected_threads; - resurrected_threads = tmp; + + // ThreadFinished and ThreadComplete: we have to keep + // these on the all_threads list until they + // become garbage, because they might get + // pending exceptions. + switch (t->what_next) { + case ThreadKilled: + case ThreadComplete: + continue; + default: + tmp = t; + evacuate((StgClosure **)&tmp); + tmp->global_link = resurrected_threads; + resurrected_threads = tmp; + } } } } @@ -338,7 +357,11 @@ traverseBlackholeQueue (void) } } evacuate((StgClosure **)&t); - if (prev) prev->_link = t; + if (prev) { + prev->_link = t; + } else { + blackhole_queue = t; + } // no write barrier when on the blackhole queue, // because we traverse the whole queue on every GC. flag = rtsTrue; @@ -367,8 +390,9 @@ markWeakPtrList ( void ) last_w = &weak_ptr_list; for (w = weak_ptr_list; w; w = w->link) { // w might be WEAK, EVACUATED, or DEAD_WEAK (actually CON_STATIC) here - ASSERT(w->header.info == &stg_DEAD_WEAK_info - || get_itbl(w)->type == WEAK || get_itbl(w)->type == EVACUATED); + ASSERT(IS_FORWARDING_PTR(w->header.info) + || w->header.info == &stg_DEAD_WEAK_info + || get_itbl(w)->type == WEAK); tmp = w; evacuate((StgClosure **)&tmp); *last_w = w;