diff --git a/primitives/primproc/batchprimitiveprocessor.cpp b/primitives/primproc/batchprimitiveprocessor.cpp
index 8678e1381..6f15cb7dd 100755
--- a/primitives/primproc/batchprimitiveprocessor.cpp
+++ b/primitives/primproc/batchprimitiveprocessor.cpp
@@ -112,6 +112,7 @@ BatchPrimitiveProcessor::BatchPrimitiveProcessor() :
 {
 	pp.setLogicalBlockMode(true);
 	pp.setBlockPtr((int *) blockData);
+    pthread_mutex_init(&objLock,NULL);
 }
 
 BatchPrimitiveProcessor::BatchPrimitiveProcessor(ByteStream &b, double prefetch,
@@ -153,6 +154,7 @@ BatchPrimitiveProcessor::BatchPrimitiveProcessor(ByteStream &b, double prefetch,
 	pp.setLogicalBlockMode(true);
 	pp.setBlockPtr((int *) blockData);
 	sendThread = bppst;
+    pthread_mutex_init(&objLock, NULL);
 	initBPP(b);
 // 	cerr << "made a BPP\n";
 }
@@ -175,6 +177,7 @@ BatchPrimitiveProcessor::~BatchPrimitiveProcessor()
 		counterLock.lock();
 	}
 	counterLock.unlock();
+    pthread_mutex_destroy(&objLock);
 }
 
 /**
@@ -233,7 +236,7 @@ void BatchPrimitiveProcessor::initBPP(ByteStream &bs)
 	}
 
 	if (doJoin) {
-		objLock.lock();
+		pthread_mutex_lock(&objLock);
 		if (ot == ROW_GROUP) {
 			bs >> joinerCount;
 // 			cout << "joinerCount = " << joinerCount << endl;
@@ -325,7 +328,7 @@ void BatchPrimitiveProcessor::initBPP(ByteStream &bs)
 			joiner.reset(new Joiner((bool) tmp8));
 		}
 #ifdef __FreeBSD__
-		objLock.unlock();
+		pthread_mutex_unlock(&objLock);
 #endif
 	}
 
@@ -401,7 +404,7 @@ void BatchPrimitiveProcessor::resetBPP(ByteStream &bs, const SP_UM_MUTEX& w,
 	uint32_t i;
 	vector<uint64_t> preloads;
 
-	objLock.lock();
+	pthread_mutex_lock(&objLock);
 
 	writelock = w;
 	sock = s;
@@ -452,7 +455,7 @@ void BatchPrimitiveProcessor::resetBPP(ByteStream &bs, const SP_UM_MUTEX& w,
 
 	buildVSSCache(count);
 #ifdef __FreeBSD__
-	objLock.unlock();
+	pthread_mutex_unlock(&objLock);
 #endif
 }
 
@@ -599,7 +602,7 @@ int BatchPrimitiveProcessor::endOfJoiner()
 #endif
 
 #ifndef __FreeBSD__
-	objLock.unlock();
+	pthread_mutex_unlock(&objLock);
 #endif
 	return 0;
 }
@@ -1486,7 +1489,7 @@ void BatchPrimitiveProcessor::execute()
 #endif
 
 #ifndef __FreeBSD__
-		objLock.unlock();
+		pthread_mutex_unlock(&objLock);
 #endif
 		throw n;   // need to pass this through to BPPSeeder
 	}
@@ -1777,12 +1780,7 @@ int BatchPrimitiveProcessor::operator()()
 
 	vssCache.clear();
 #ifndef __FreeBSD__
-	// If we've been aborted the lock *may* have been released already
-	// By doing try_lock, we ensure the unlock will work whether it was
-	// locked or not.
-	if (sendThread->aborted())
-		objLock.try_lock();
-	objLock.unlock();
+	pthread_mutex_unlock(&objLock);
 #endif
 	freeLargeBuffers();
 #ifdef PRIMPROC_STOPWATCH
@@ -1881,7 +1879,7 @@ SBPP BatchPrimitiveProcessor::duplicate()
 	}
 	bpp->doJoin = doJoin;
 	if (doJoin) {
-		bpp->objLock.lock();
+		pthread_mutex_lock(&bpp->objLock);
 		bpp->joinerSize = joinerSize;
 		if (ot == ROW_GROUP) {
 			/* There are add'l join vars, but only these are necessary for processing
@@ -1921,7 +1919,7 @@ SBPP BatchPrimitiveProcessor::duplicate()
 		else
 			bpp->joiner = joiner;
 #ifdef __FreeBSD__
-		bpp->objLock.unlock();
+		pthread_mutex_unlock(&bpp->objLock);
 #endif
 	}
 
diff --git a/primitives/primproc/batchprimitiveprocessor.h b/primitives/primproc/batchprimitiveprocessor.h
index c57479ef9..ca782b3c7 100755
--- a/primitives/primproc/batchprimitiveprocessor.h
+++ b/primitives/primproc/batchprimitiveprocessor.h
@@ -121,7 +121,7 @@ class BatchPrimitiveProcessor
 
 		// these two functions are used by BPPV to create BPP instances
 		// on demand.  TRY not to use unlock() for anything else.
-		void unlock() { objLock.try_lock(); objLock.unlock(); }
+		void unlock() { pthread_mutex_unlock(&objLock); }
 		bool hasJoin() { return doJoin; }
 	private:
 		BatchPrimitiveProcessor();
@@ -200,7 +200,12 @@ class BatchPrimitiveProcessor
 		messageqcpp::SBS serialized;
 		SP_UM_MUTEX  writelock;
 
-		boost::mutex objLock;
+        // MCOL-744 using pthread mutex instead of Boost mutex because
+        // in it is possible that this lock could be unlocked when it is
+        // already unlocked. In Ubuntu 16.04's Boost this triggers a
+        // crash. Whilst it is very hard to hit this it is still bad.
+        // Longer term TODO: fix/remove objLock and/or refactor BPP
+		pthread_mutex_t objLock;
 		bool LBIDTrace;
 		bool fBusy;