HPCC-13597 Potential roxie core when a query fails

Safer fix (previous one MAY have caused deadlock?)

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>

roxie/ccd/ccdserver.cpp

@@ -5321,6 +5321,7 @@ IRoxieServerActivityFactory *createRoxieServerInlineTableActivityFactory(unsigne
 class CRoxieServerWorkUnitReadActivity : public CRoxieServerActivity
 {
     IHThorWorkunitReadArg &helper;
+    CriticalSection readerCrit;
     Owned<IWorkUnitRowReader> wuReader; // MORE - can we use IRoxieInput instead?
 public:
     CRoxieServerWorkUnitReadActivity(const IRoxieServerActivityFactory *_factory, IProbeManager *_probeManager)
@@ -5348,8 +5349,10 @@ public:
 
     virtual void reset() 
     {
-        CriticalBlock b(statecrit);
-        wuReader.clear();
+        {
+            CriticalBlock b(readerCrit);
+            wuReader.clear();
+        }
         CRoxieServerActivity::reset(); 
     };
 
@@ -5357,11 +5360,15 @@ public:
 
     virtual const void *nextInGroup()
     {
-        CriticalBlock b(statecrit);
         ActivityTimer t(totalCycles, timeActivities);
-        if (!wuReader)
-            return NULL;
-        const void *ret = wuReader->nextInGroup();
+        Linked<IWorkUnitRowReader> useReader;
+        {
+            CriticalBlock b(readerCrit);
+            if (!wuReader)
+                return NULL;
+            useReader.set(wuReader);
+        }
+        const void *ret = useReader->nextInGroup();
         if (ret)
             processed++;
         return ret;
@@ -5747,6 +5754,7 @@ protected:
 class CRoxieServerLocalResultReadActivity : public CRoxieServerActivity
 {
     IHThorLocalResultReadArg &helper;
+    CriticalSection iterCrit;
     Owned<IRoxieInput> iter;
     ILocalGraphEx * graph;
     unsigned graphId;
@@ -5775,18 +5783,24 @@ public:
 
     virtual void reset() 
     {
-        CriticalBlock b(statecrit);
-        iter.clear();
+        {
+            CriticalBlock b(iterCrit);
+            iter.clear();
+        }
         CRoxieServerActivity::reset(); 
     };
 
     virtual const void *nextInGroup()
     {
-        CriticalBlock b(statecrit);
         ActivityTimer t(totalCycles, timeActivities);
-        if (!iter)
-            return NULL;
-        const void * next = iter->nextInGroup();
+        Linked<IRoxieInput> useIter;
+        {
+            CriticalBlock b(iterCrit);
+            if (!iter)
+                return NULL;
+            useIter.set(iter);
+        }
+        const void * next = useIter->nextInGroup();
         if (next)
         {
             processed++;
@@ -6076,6 +6090,7 @@ class CRoxieServerGraphLoopResultReadActivity : public CRoxieServerActivity
 {
 protected:
     IHThorGraphLoopResultReadArg &helper;
+    CriticalSection iterCrit;
     Owned<IRoxieInput> iter;
     ILocalGraphEx * graph;
     unsigned graphId;
@@ -6126,18 +6141,26 @@ public:
 
     virtual void reset() 
     {
-        CriticalBlock b(statecrit);
-        if (iter)
-            iter->reset();
-        iter.clear();
+        {
+            CriticalBlock b(iterCrit);
+            if (iter)
+                iter->reset();
+            iter.clear();
+        }
         CRoxieServerActivity::reset(); 
     };
 
     virtual const void *nextInGroup()
     {
-        CriticalBlock b(statecrit);
         ActivityTimer t(totalCycles, timeActivities);
-        const void * next = iter ? iter->nextInGroup() : NULL;
+        Linked<IRoxieInput> useIter;
+        {
+            CriticalBlock b(iterCrit);
+            if (!iter)
+                return NULL;
+            useIter.set(iter);
+        }
+        const void * next = useIter->nextInGroup();
         if (next)
         {
             processed++;