fix(DEC):MCOL-5805,5808 to resolve UM-only node crash inside DEC when there is no local PP to send the local requests to. (#3350)

* Revert "fix(DEC): MCOL-5602 fixing potentially endless loop in DEC (#3049)"

This reverts commit 1d416bc6ed.

* fix(DEC):MCOL-5805,5808 to resolve UM-only node crash inside DEC when there is no local PP to send the local requests to.

dbcon/joblist/distributedenginecomm.cpp

@@ -181,6 +181,17 @@ struct QueueShutdown
 
 namespace joblist
 {
+
+bool isDefaultLocalConnectionId(const uint32_t connectionId)
+{
+  return defaultLocalConnectionId() == connectionId;
+}
+
+bool needToSendToLocalPM(const bool isExeMgr, const uint32_t connectionId)
+{
+  return isExeMgr && !isDefaultLocalConnectionId(connectionId);
+}
+
 DistributedEngineComm* DistributedEngineComm::fInstance = 0;
 
 /*static*/
@@ -356,6 +367,8 @@ int32_t DistributedEngineComm::Setup()
 
   fWlock.swap(newLocks);
   fPmConnections.swap(newClients);
+  // memory barrier to prevent the pmCount assignment migrating upward
+  atomicops::atomicMb();
   pmCount = newPmCount;
 
   newLocks.clear();
@@ -417,14 +430,14 @@ Error:
   for (map_tok = fSessionMessages.begin(); map_tok != fSessionMessages.end(); ++map_tok)
   {
     map_tok->second->queue.clear();
-    ++map_tok->second->unackedWork[0];
+    (void)atomicops::atomicInc(&map_tok->second->unackedWork[0]);
     map_tok->second->queue.push(sbs);
   }
   lk.unlock();
 
   if (fIsExeMgr)
   {
-    const uint32_t originalPMCount = pmCount;
+    decltype(pmCount) originalPMCount = pmCount;
     // Re-establish if a remote PM restarted.
     std::this_thread::sleep_for(std::chrono::seconds(3));
     auto rc = Setup();
@@ -645,7 +658,7 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
                                      size_t queueSize)
 {
   ISMPacketHeader* ism;
-  size_t l_msgCount = msgs.size();
+  uint32_t l_msgCount = msgs.size();
 
   /* If the current queue size > target, do nothing.
    * If the original queue size > target, ACK the msgs below the target.
@@ -653,13 +666,14 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
   if (!mqe->throttled || queueSize >= mqe->targetQueueSize)
   {
     /* no acks will be sent, but update unackedwork to keep the #s accurate */
+    uint16_t numack = 0;
     uint32_t sockidx = 0;
 
     while (l_msgCount > 0)
     {
-      size_t numAcked = subsMsgCounterAndRotatePM(mqe, l_msgCount, &sockidx);
+      nextPMToACK(mqe, l_msgCount, &sockidx, &numack);
-      idbassert(numAcked <= l_msgCount);
+      idbassert(numack <= l_msgCount);
-      l_msgCount -= numAcked;
+      l_msgCount -= numack;
     }
 
     return;
@@ -674,8 +688,9 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
   {
     /* update unackedwork for the overage that will never be acked */
     int64_t overage = queueSize + totalMsgSize - mqe->targetQueueSize;
+    uint16_t numack = 0;
     uint32_t sockidx = 0;
-    size_t msgsToIgnore;
+    uint32_t msgsToIgnore;
 
     for (msgsToIgnore = 0; overage >= 0; msgsToIgnore++)
       overage -= msgs[msgsToIgnore]->lengthWithHdrOverhead();
@@ -687,15 +702,16 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
 
     while (msgsToIgnore > 0)
     {
-      size_t numAcked = subsMsgCounterAndRotatePM(mqe, msgsToIgnore, &sockidx);
+      nextPMToACK(mqe, msgsToIgnore, &sockidx, &numack);
-      idbassert(numAcked <= msgsToIgnore);
+      idbassert(numack <= msgsToIgnore);
-      msgsToIgnore -= numAcked;
+      msgsToIgnore -= numack;
     }
   }
 
   if (l_msgCount > 0)
   {
     SBS msg(new ByteStream(sizeof(ISMPacketHeader)));
+    uint16_t* toAck;
     vector<bool> pmAcked(pmCount, false);
 
     ism = (ISMPacketHeader*)msg->getInputPtr();
@@ -705,6 +721,7 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
 
     ism->Interleave = uniqueID;
     ism->Command = BATCH_PRIMITIVE_ACK;
+    toAck = &ism->Size;
 
     msg->advanceInputPtr(sizeof(ISMPacketHeader));
     // There must be only one local connection here.
@@ -716,21 +733,10 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
 
       /* This will reset the ACK field in the Bytestream directly, and nothing
        * else needs to change if multiple msgs are sent. */
-      size_t numAcked = subsMsgCounterAndRotatePM(mqe, l_msgCount, &sockIndex);
+      nextPMToACK(mqe, l_msgCount, &sockIndex, toAck);
-      // Potential truncation here from size_t to 16 bits.
+      idbassert(*toAck <= l_msgCount);
-      ism->Size = static_cast<uint16_t>(
+      l_msgCount -= *toAck;
-          std::min(static_cast<size_t>(std::numeric_limits<uint16_t>::max()), numAcked));
+      if (sockIndex == localConnectionId_ && needToSendToLocalPM(fIsExeMgr, sockIndex))
-      idbassert(numAcked <= l_msgCount);
-      l_msgCount -= numAcked;
-
-      // We get some logs if the above mentioned truncation happens.
-      if (numAcked > std::numeric_limits<uint16_t>::max())
-      {
-        cerr << "DEC::sendAcks(): msgs acked number [" << numAcked
-             << "] overflows PrimMsg protocol header field capacity 2^16." << std::endl;
-      }
-
-      if (sockIndex == localConnectionId_ && fIsExeMgr)
       {
         sendToLocal = true;
         continue;
@@ -756,7 +762,7 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
 
       if (totalUnackedWork == 0)
       {
-        ism->Size = 1;  // size of the batch acked
+        *toAck = 1;
 
         for (uint32_t i = 0; i < pmCount; ++i)
         {
@@ -771,7 +777,7 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
             writeToClient(i, ackCommand);
           }
         }
-        if (!pmAcked[localConnectionId_] && fIsExeMgr)
+        if (needToSendToLocalPM(fIsExeMgr, localConnectionId_) && !pmAcked[localConnectionId_])
         {
           writeToClient(localConnectionId_, msg);
         }
@@ -780,8 +786,8 @@ void DistributedEngineComm::sendAcks(uint32_t uniqueID, const vector<SBS>& msgs,
   }
 }
 
-size_t DistributedEngineComm::subsMsgCounterAndRotatePM(boost::shared_ptr<MQE> mqe, const size_t maxAck,
+void DistributedEngineComm::nextPMToACK(boost::shared_ptr<MQE> mqe, uint32_t maxAck, uint32_t* sockIndex,
-                                                        uint32_t* sockIndex)
+                                        uint16_t* numToAck)
 {
   uint32_t& nextIndex = mqe->ackSocketIndex;
 
@@ -789,57 +795,56 @@ size_t DistributedEngineComm::subsMsgCounterAndRotatePM(boost::shared_ptr<MQE> m
    * the locking env, mqe->unackedWork can only grow; whatever gets latched in this fcn
    * is a safe minimum at the point of use. */
 
-  if (mqe->unackedWork[nextIndex].load() >= maxAck)
+  if (mqe->unackedWork[nextIndex] >= maxAck)
   {
-    atomicops::atomicSubstitute(mqe->unackedWork[nextIndex], maxAck);
+    (void)atomicops::atomicSub(&mqe->unackedWork[nextIndex], maxAck);
     *sockIndex = nextIndex;
+    // FIXME: we're going to truncate here from 32 to 16 bits. Hopefully this will always fit...
+    *numToAck = maxAck;
 
     if (pmCount > 0)
       nextIndex = (nextIndex + 1) % pmCount;
 
-    return maxAck;
+    return;
   }
   else
   {
     for (int i = pmCount - 1; i >= 0; --i)
     {
-      const size_t curVal = mqe->unackedWork[nextIndex].load();
+      uint32_t curVal = mqe->unackedWork[nextIndex];
-      const size_t unackedWork = std::min(curVal, maxAck);
+      uint32_t unackedWork = (curVal > maxAck ? maxAck : curVal);
+
       if (unackedWork > 0)
       {
-        atomicops::atomicSubstitute(mqe->unackedWork[nextIndex], unackedWork);
+        (void)atomicops::atomicSub(&mqe->unackedWork[nextIndex], unackedWork);
-
         *sockIndex = nextIndex;
+        *numToAck = unackedWork;
 
         if (pmCount > 0)
           nextIndex = (nextIndex + 1) % pmCount;
 
-        return unackedWork;
+        return;
       }
 
       if (pmCount > 0)
         nextIndex = (nextIndex + 1) % pmCount;
     }
 
-    cerr << "DEC::subsMsgCounterAndRotatePM(): Couldn't find a PM to ACK! ";
+    cerr << "DEC::nextPMToACK(): Couldn't find a PM to ACK! ";
 
     for (int i = pmCount - 1; i >= 0; --i)
       cerr << mqe->unackedWork[i] << " ";
 
-    cerr << " max: " << maxAck << endl;
+    cerr << " max: " << maxAck;
+    cerr << endl;
     // make sure the returned vars are legitimate
     *sockIndex = nextIndex;
+    *numToAck = maxAck / pmCount;
 
-    // This will potentially results in invalid pmCount but it's better than crashing on 0 div.
+    if (pmCount > 0)
-    const uint32_t localPmCount = pmCount.load();
+      nextIndex = (nextIndex + 1) % pmCount;
-    if (localPmCount > 0)
-    {
-      nextIndex = (nextIndex + 1) % localPmCount;
-      return maxAck / localPmCount;
-    }
 
-    cerr << "DEC::subsMsgCounterAndRotatePM(): The number of PMs is 0.";
+    return;
-    return maxAck;
   }
 }
 
@@ -863,9 +868,11 @@ void DistributedEngineComm::setFlowControl(bool enabled, uint32_t uniqueID, boos
     }
     writeToClient(i, msg);
   }
-  if (fIsExeMgr)
+  if (needToSendToLocalPM(fIsExeMgr, localConnectionId_))
+  {
     writeToClient(localConnectionId_, msg);
   }
+}
 
 int32_t DistributedEngineComm::write(uint32_t senderID, const SBS& msg)
 {
@@ -904,7 +911,7 @@ int32_t DistributedEngineComm::write(uint32_t senderID, const SBS& msg)
               return rc;
             }
           }
-          if (fIsExeMgr)
+          if (needToSendToLocalPM(fIsExeMgr, localConnectionId_))
           {
             return writeToClient(localConnectionId_, msg);
           }
@@ -990,7 +997,7 @@ void DistributedEngineComm::addDataToOutput(SBS sbs, uint32_t connIndex, Stats*
 
   if (pmCount > 0)
   {
-    ++mqe->unackedWork[connIndex % pmCount];
+    (void)atomicops::atomicInc(&mqe->unackedWork[connIndex % pmCount]);
   }
 
   TSQSize_t queueSize = mqe->queue.push(sbs);
@@ -1112,7 +1119,7 @@ int DistributedEngineComm::writeToClient(size_t aPMIndex, const SBS& bs, uint32_
     for (map_tok = fSessionMessages.begin(); map_tok != fSessionMessages.end(); ++map_tok)
     {
       map_tok->second->queue.clear();
-      ++map_tok->second->unackedWork[0];
+      (void)atomicops::atomicInc(&map_tok->second->unackedWork[0]);
       map_tok->second->queue.push(sbs);
     }
 
@@ -1140,6 +1147,37 @@ int DistributedEngineComm::writeToClient(size_t aPMIndex, const SBS& bs, uint32_
 
     // Connection was established.
     return 1;
+    /*
+                    // reconfig the connection array
+                    ClientList tempConns;
+                    {
+                            //cout << "WARNING: DEC WRITE BROKEN PIPE " <<
+    fPmConnections[index]->otherEnd()<< endl; boost::mutex::scoped_lock onErrLock(fOnErrMutex); string
+    moduleName = fPmConnections[index]->moduleName();
+                            //cout << "module name = " << moduleName << endl;
+                            if (index >= fPmConnections.size()) return 0;
+
+                            for (uint32_t i = 0; i < fPmConnections.size(); i++)
+                            {
+                                    if (moduleName != fPmConnections[i]->moduleName())
+                                            tempConns.push_back(fPmConnections[i]);
+                            }
+                            if (tempConns.size() == fPmConnections.size()) return 0;
+                            fPmConnections.swap(tempConns);
+                            pmCount = (pmCount == 0 ? 0 : pmCount - 1);
+                    }
+    // send alarm
+    ALARMManager alarmMgr;
+    string alarmItem("UNKNOWN");
+
+    if (index < fPmConnections.size())
+    {
+        alarmItem = fPmConnections[index]->addr2String();
+    }
+
+    alarmItem.append(" PrimProc");
+    alarmMgr.sendAlarmReport(alarmItem.c_str(), oam::CONN_FAILURE, SET);
+    */
   }
   return 0;
 }
@@ -1195,15 +1233,9 @@ DistributedEngineComm::MQE::MQE(const uint32_t pCount, const uint32_t initialInt
                                 const uint64_t flowControlEnableBytesThresh)
  : ackSocketIndex(0), pmCount(pCount), hasBigMsgs(false), targetQueueSize(flowControlEnableBytesThresh)
 {
+  unackedWork.reset(new volatile uint32_t[pmCount]);
   interleaver.reset(new uint32_t[pmCount]);
-  const uint32_t localPmCount = pmCount;
+  memset((void*)unackedWork.get(), 0, pmCount * sizeof(uint32_t));
-  AtomicSizeVec s(localPmCount);
-  for (size_t i = 0; i < localPmCount; ++i)
-  {
-    s[i].store(0);
-  }
-  unackedWork.swap(s);
-
   uint32_t interleaverValue = initialInterleaverValue;
   initialConnectionId = initialInterleaverValue;
   for (size_t pmId = 0; pmId < pmCount; ++pmId)

dbcon/joblist/distributedenginecomm.h

@@ -69,6 +69,11 @@ class Config;
  */
 namespace joblist
 {
+constexpr uint32_t defaultLocalConnectionId()
+{
+  return std::numeric_limits<uint32_t>::max();
+}
+
 class DECEventListener
 {
  public:
@@ -225,7 +230,6 @@ class DistributedEngineComm
 
   // A queue of ByteStreams coming in from PrimProc heading for a JobStep
   typedef ThreadSafeQueue<messageqcpp::SBS> StepMsgQueue;
-  using AtomicSizeVec = std::vector<std::atomic<size_t>>;
 
   // Creates a ByteStream as a command for Primitive Server and initializes it with a given `command`,
   // `uniqueID` and `size`.
@@ -240,7 +244,7 @@ class DistributedEngineComm
     messageqcpp::Stats stats;
     StepMsgQueue queue;
     uint32_t ackSocketIndex;
-    AtomicSizeVec unackedWork;
+    boost::scoped_array<volatile uint32_t> unackedWork;
     boost::scoped_array<uint32_t> interleaver;
     uint32_t initialConnectionId;
     uint32_t pmCount;
@@ -288,7 +292,7 @@ class DistributedEngineComm
   std::mutex fMlock;     // sessionMessages mutex
   std::vector<std::shared_ptr<std::mutex>> fWlock;  // PrimProc socket write mutexes
   bool fBusy;
-  std::atomic<uint32_t> pmCount;
+  volatile uint32_t pmCount;
   boost::mutex fOnErrMutex;  // to lock function scope to reset pmconnections under error condition
   boost::mutex fSetupMutex;
 
@@ -310,13 +314,13 @@ class DistributedEngineComm
 
   void sendAcks(uint32_t uniqueID, const std::vector<messageqcpp::SBS>& msgs, boost::shared_ptr<MQE> mqe,
                 size_t qSize);
-  size_t subsMsgCounterAndRotatePM(boost::shared_ptr<MQE> mqe, const size_t maxAck, uint32_t* sockIndex);
+  void nextPMToACK(boost::shared_ptr<MQE> mqe, uint32_t maxAck, uint32_t* sockIndex, uint16_t* numToAck);
   void setFlowControl(bool enable, uint32_t uniqueID, boost::shared_ptr<MQE> mqe);
   void doHasBigMsgs(boost::shared_ptr<MQE> mqe, uint64_t targetSize);
   boost::mutex ackLock;
 
   // localConnectionId_ is set running Setup() method
-  uint32_t localConnectionId_ = std::numeric_limits<uint32_t>::max();
+  uint32_t localConnectionId_ = defaultLocalConnectionId();
   std::vector<struct in_addr> localNetIfaceSins_;
   std::mutex inMemoryEM2PPExchMutex_;
   std::condition_variable inMemoryEM2PPExchCV_;

utils/common/atomicops.h

@@ -22,7 +22,6 @@
 #include <unistd.h>
 #include <stdint.h>
 #include <sched.h>
-#include <atomic>
 
 /*
 This is an attempt to wrap the differneces between Windows and Linux around atomic ops.
@@ -93,15 +92,4 @@ inline void atomicYield()
   sched_yield();
 }
 
-// This f assumes decrement is smaller than minuend.
-template <typename T>
-inline void atomicSubstitute(typename std::atomic<T>& minuend, T decrement)
-{
-  T expected = minuend.load();
-  do
-  {
-    expected = minuend.load();
-  } while (!minuend.compare_exchange_weak(expected, expected - decrement));
-}
-
 }  // namespace atomicops