196383 2019-03-28 17:32:59 -0700 Worklist::setNumberOfThreads seems incompatible with how we lock elsewhere 2019-03-28 17:33:23 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified NEW P2 Normal --- 1 saam webkit-unassigned benjamin fpizlo ggaren gskachkov guijemont keith_miller mark.lam msaboff rmorisset saam ticaiolima tzagallo ysuzuki oldest_to_newest 1522304 0 saam 2019-03-28 17:32:59 -0700 E.g, there is no way this is right anymore: ``` void Worklist::visitWeakReferences(SlotVisitor& visitor) { VM* vm = visitor.heap()->vm(); { LockHolder locker(*m_lock); for (PlanMap::iterator iter = m_plans.begin(); iter != m_plans.end(); ++iter) { Plan* plan = iter->value.get(); if (plan->vm() != vm) continue; plan->checkLivenessAndVisitChildren(visitor); } } // This loop doesn't need locking because: // (1) no new threads can be added to m_threads. Hence, it is immutable and needs no locks. // (2) ThreadData::m_safepoint is protected by that thread's m_rightToRun which we must be // holding here because of a prior call to suspendAllThreads(). for (unsigned i = m_threads.size(); i--;) { ThreadData* data = m_threads[i].get(); Safepoint* safepoint = data->m_safepoint; if (safepoint && safepoint->vm() == vm) safepoint->checkLivenessAndVisitChildren(visitor); } } ```