diff options
| -rw-r--r-- | lib/pure/concurrency/threadpool.nim | 51 |
1 files changed, 47 insertions, 4 deletions
diff --git a/lib/pure/concurrency/threadpool.nim b/lib/pure/concurrency/threadpool.nim index 9490dbbd5..8cdb83e19 100644 --- a/lib/pure/concurrency/threadpool.nim +++ b/lib/pure/concurrency/threadpool.nim @@ -297,9 +297,20 @@ var gSomeReady : Semaphore readyWorker: ptr Worker +# A workaround for recursion deadlock issue +# https://github.com/nim-lang/Nim/issues/4597 +var + numSlavesLock: Lock + numSlavesRunning {.guard: numSlavesLock}: int + numSlavesWaiting {.guard: numSlavesLock}: int + isSlave {.threadvar.}: bool + +numSlavesLock.initLock + gSomeReady.initSemaphore() proc slave(w: ptr Worker) {.thread.} = + isSlave = true while true: when declared(atomicStoreN): atomicStoreN(addr(w.ready), true, ATOMIC_SEQ_CST) @@ -311,7 +322,15 @@ proc slave(w: ptr Worker) {.thread.} = # XXX Somebody needs to look into this (why does this assertion fail # in Visual Studio?) when not defined(vcc): assert(not w.ready) + + withLock numSlavesLock: + inc numSlavesRunning + w.f(w, w.data) + + withLock numSlavesLock: + dec numSlavesRunning + if w.q.len != 0: w.cleanFlowVars if w.shutdown: w.shutdown = false @@ -464,10 +483,34 @@ proc nimSpawn3(fn: WorkerProc; data: pointer) {.compilerProc.} = fn(self, data) await(self.taskStarted) return - else: - await(gSomeReady) - else: - await(gSomeReady) + + if isSlave: + # Run under lock until `numSlavesWaiting` increment to avoid a + # race (otherwise two last threads might start waiting together) + withLock numSlavesLock: + if numSlavesRunning <= numSlavesWaiting + 1: + # All the other slaves are waiting + # If we wait now, we-re deadlocked until + # an external spawn happens ! + if currentPoolSize < maxPoolSize: + if not workersData[currentPoolSize].initialized: + activateWorkerThread(currentPoolSize) + let w = addr(workersData[currentPoolSize]) + atomicInc currentPoolSize + if selectWorker(w, fn, data): + return + else: + # There is no place in the pool. We're deadlocked. + # echo "Deadlock!" + discard + + inc numSlavesWaiting + + await(gSomeReady) + + if isSlave: + withLock numSlavesLock: + dec numSlavesWaiting var distinguishedLock: Lock |