/* Run the global destruction phase. */ void MVM_gc_global_destruction(MVMThreadContext *tc) { char *nursery_tmp; /* Fake a nursery collection run by swapping the semi- * space nurseries. */ nursery_tmp = tc->nursery_fromspace; tc->nursery_fromspace = tc->nursery_tospace; tc->nursery_tospace = nursery_tmp; /* Run the objects' finalizers */ MVM_gc_collect_free_nursery_uncopied(tc, tc->nursery_alloc); MVM_gc_root_gen2_cleanup(tc); MVM_gc_collect_free_gen2_unmarked(tc, 1); MVM_gc_collect_free_stables(tc); }
/* Run the global destruction phase. */ void MVM_gc_global_destruction(MVMThreadContext *tc) { char *nursery_tmp; /* Must wait until we're the only thread... */ while (tc->instance->num_user_threads) { GC_SYNC_POINT(tc); MVM_platform_thread_yield(); } /* Fake a nursery collection run by swapping the semi- * space nurseries. */ nursery_tmp = tc->nursery_fromspace; tc->nursery_fromspace = tc->nursery_tospace; tc->nursery_tospace = nursery_tmp; /* Run the objects' finalizers */ MVM_gc_collect_free_nursery_uncopied(tc, tc->nursery_alloc); MVM_gc_root_gen2_cleanup(tc); MVM_gc_collect_free_gen2_unmarked(tc); MVM_gc_collect_free_stables(tc); }
static void finish_gc(MVMThreadContext *tc, MVMuint8 gen, MVMuint8 is_coordinator) { MVMuint32 i, did_work; /* Do any extra work that we have been passed. */ GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : doing any work in thread in-trays\n"); did_work = 1; while (did_work) { did_work = 0; for (i = 0; i < tc->gc_work_count; i++) did_work += process_in_tray(tc->gc_work[i].tc, gen); } /* Decrement gc_finish to say we're done, and wait for termination. */ GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Voting to finish\n"); MVM_decr(&tc->instance->gc_finish); while (MVM_load(&tc->instance->gc_finish)) { for (i = 0; i < 1000; i++) ; /* XXX Something HT-efficienter. */ /* XXX Here we can look to see if we got passed any work, and if so * try to un-vote. */ } GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Termination agreed\n"); /* Co-ordinator should do final check over all the in-trays, and trigger * collection until all is settled. Rest should wait. Additionally, after * in-trays are settled, coordinator walks threads looking for anything * that needs adding to the finalize queue. It then will make another * iteration over in-trays to handle cross-thread references to objects * needing finalization. For full collections, collected objects are then * cleaned from all inter-generational sets, and finally any objects to * be freed at the fixed size allocator's next safepoint are freed. */ if (is_coordinator) { GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Co-ordinator handling in-tray clearing completion\n"); clear_intrays(tc, gen); GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Co-ordinator handling finalizers\n"); MVM_finalize_walk_queues(tc, gen); clear_intrays(tc, gen); if (gen == MVMGCGenerations_Both) { MVMThread *cur_thread = (MVMThread *)MVM_load(&tc->instance->threads); GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Co-ordinator handling inter-gen root cleanup\n"); while (cur_thread) { if (cur_thread->body.tc) MVM_gc_root_gen2_cleanup(cur_thread->body.tc); cur_thread = cur_thread->body.next; } } GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Co-ordinator handling fixed-size allocator safepoint frees\n"); MVM_fixed_size_safepoint(tc, tc->instance->fsa); GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Co-ordinator signalling in-trays clear\n"); MVM_store(&tc->instance->gc_intrays_clearing, 0); } else { GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Waiting for in-tray clearing completion\n"); while (MVM_load(&tc->instance->gc_intrays_clearing)) for (i = 0; i < 1000; i++) ; /* XXX Something HT-efficienter. */ GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Got in-tray clearing complete notice\n"); } /* Reset GC status flags. This is also where thread destruction happens, * and it needs to happen before we acknowledge this GC run is finished. */ for (i = 0; i < tc->gc_work_count; i++) { MVMThreadContext *other = tc->gc_work[i].tc; MVMThread *thread_obj = other->thread_obj; if (MVM_load(&thread_obj->body.stage) == MVM_thread_stage_clearing_nursery) { GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : transferring gen2 of thread %d\n", other->thread_id); MVM_gc_gen2_transfer(other, tc); GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : destroying thread %d\n", other->thread_id); MVM_tc_destroy(other); tc->gc_work[i].tc = thread_obj->body.tc = NULL; MVM_store(&thread_obj->body.stage, MVM_thread_stage_destroyed); } else { if (MVM_load(&thread_obj->body.stage) == MVM_thread_stage_exited) { /* Don't bother freeing gen2; we'll do it next time */ MVM_store(&thread_obj->body.stage, MVM_thread_stage_clearing_nursery); GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : set thread %d clearing nursery stage to %d\n", other->thread_id, (int)MVM_load(&thread_obj->body.stage)); } MVM_cas(&other->gc_status, MVMGCStatus_STOLEN, MVMGCStatus_UNABLE); MVM_cas(&other->gc_status, MVMGCStatus_INTERRUPT, MVMGCStatus_NONE); } } /* Signal acknowledgement of completing the cleanup, * except for STables, and if we're the final to do * so, free the STables, which have been linked. */ if (MVM_decr(&tc->instance->gc_ack) == 2) { /* Set it to zero (we're guaranteed the only ones trying to write to * it here). Actual STable free in MVM_gc_enter_from_allocator. */ MVM_store(&tc->instance->gc_ack, 0); } }
/* Does a garbage collection run. Exactly what it does is configured by the * couple of arguments that it takes. * * The what_to_do argument specifies where it should look for things to add * to the worklist: everywhere, just at thread local stuff, or just in the * thread's in-tray. * * The gen argument specifies whether to collect the nursery or both of the * generations. Nursery collection is done by semi-space copying. Once an * object is seen/copied once in the nursery (may be tuned in the future to * twice or so - we'll see) then it is not copied to tospace, but instead * promoted to the second generation. If we are collecting generation 2 also, * then objects that are alive in the second generation are simply marked. * Since the second generation is managed as a set of sized pools, there is * much less motivation for any kind of copying/compaction; the internal * fragmentation that makes finding a right-sized gap problematic will not * happen. * * Note that it adds the roots and processes them in phases, to try to avoid * building up a huge worklist. */ void MVM_gc_collect(MVMThreadContext *tc, MVMuint8 what_to_do, MVMuint8 gen) { /* Create a GC worklist. */ MVMGCWorklist *worklist = MVM_gc_worklist_create(tc, gen != MVMGCGenerations_Nursery); /* Initialize work passing data structure. */ WorkToPass wtp; wtp.num_target_threads = 0; wtp.target_work = NULL; /* If we're starting a run (as opposed to just coming back here to do a * little more work we got after we first thought we were done...) */ if (what_to_do != MVMGCWhatToDo_InTray) { /* Swap fromspace and tospace. */ void * fromspace = tc->nursery_tospace; void * tospace = tc->nursery_fromspace; tc->nursery_fromspace = fromspace; tc->nursery_tospace = tospace; /* Reset nursery allocation pointers to the new tospace. */ tc->nursery_alloc = tospace; tc->nursery_alloc_limit = (char *)tc->nursery_alloc + MVM_NURSERY_SIZE; MVM_gc_worklist_add(tc, worklist, &tc->thread_obj); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from thread_obj\n", worklist->items); process_worklist(tc, worklist, &wtp, gen); /* Add permanent roots and process them; only one thread will do * this, since they are instance-wide. */ if (what_to_do != MVMGCWhatToDo_NoInstance) { MVM_gc_root_add_permanents_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from instance permanents\n", worklist->items); process_worklist(tc, worklist, &wtp, gen); MVM_gc_root_add_instance_roots_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from instance roots\n", worklist->items); process_worklist(tc, worklist, &wtp, gen); } /* Add per-thread state to worklist and process it. */ MVM_gc_root_add_tc_roots_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from TC objects\n", worklist->items); process_worklist(tc, worklist, &wtp, gen); /* Add current frame to worklist. */ MVM_gc_worklist_add_frame(tc, worklist, tc->cur_frame); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from current frame\n", worklist->items); process_worklist(tc, worklist, &wtp, gen); /* Add temporary roots and process them (these are per-thread). */ MVM_gc_root_add_temps_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from thread temps\n", worklist->items); process_worklist(tc, worklist, &wtp, gen); /* Add things that are roots for the first generation because they are * pointed to by objects in the second generation and process them * (also per-thread). Note we need not do this if we're doing a full * collection anyway (in fact, we must not for correctness, otherwise * the gen2 rooting keeps them alive forever). */ if (gen == MVMGCGenerations_Nursery) { MVM_gc_root_add_gen2s_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from gen2 \n", worklist->items); process_worklist(tc, worklist, &wtp, gen); } /* Find roots in frames and process them. */ if (tc->cur_frame) { MVM_gc_worklist_add_frame(tc, worklist, tc->cur_frame); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from cur_frame \n", worklist->items); process_worklist(tc, worklist, &wtp, gen); } /* Process anything in the in-tray. */ add_in_tray_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from in tray \n", worklist->items); process_worklist(tc, worklist, &wtp, gen); /* At this point, we have probably done most of the work we will * need to (only get more if another thread passes us more); zero * out the remaining tospace. */ memset(tc->nursery_alloc, 0, (char *)tc->nursery_alloc_limit - (char *)tc->nursery_alloc); } else { /* We just need to process anything in the in-tray. */ add_in_tray_to_worklist(tc, worklist); GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from in tray \n", worklist->items); process_worklist(tc, worklist, &wtp, gen); } /* Destroy the worklist. */ MVM_gc_worklist_destroy(tc, worklist); /* Pass any work for other threads we accumulated but that didn't trigger * the work passing threshold, then cleanup work passing list. */ if (wtp.num_target_threads) { pass_leftover_work(tc, &wtp); free(wtp.target_work); } /* If it was a full collection, some of the things in gen2 that we root * due to point to gen1 objects may be dead. */ if (gen != MVMGCGenerations_Nursery) MVM_gc_root_gen2_cleanup(tc); }