2 files changed, 13 insertions, 7 deletions
diff --git a/cpp/src/qpid/broker/SessionHandler.cpp b/cpp/src/qpid/broker/SessionHandler.cpp
index 1d0e67f6ab..0dafcba7bd 100644
--- a/cpp/src/qpid/broker/SessionHandler.cpp
+++ b/cpp/src/qpid/broker/SessionHandler.cpp
@@ -81,12 +81,14 @@ void SessionHandler::handleIn(AMQFrame& f) {
 }
 
 void SessionHandler::handleOut(AMQFrame& f) {
-    if (!session.get())
-        throw InternalErrorException(
-            QPID_MSG("attempt to send frame on detached channel."));
-    channel.handle(f);          // Send it.
-    if (session->sent(f))
-        peerSession.solicitAck();
+    ConditionalScopedLock<Semaphore> s(suspension);
+    if (s.lockAcquired() && session.get() && session->isAttached()) {
+        channel.handle(f);          // Send it.
+        if (session->sent(f))
+            peerSession.solicitAck();
+    } else {
+        QPID_LOG(warning, "Dropping frame as session is no longer attached to a channel: " << f);
+    }
 }
 
 void SessionHandler::assertAttached(const char* method) const {
@@ -150,7 +152,8 @@ void  SessionHandler::closed(uint16_t replyCode, const string& replyText) {
 }
 
 void SessionHandler::localSuspend() {
-    if (session.get()) {
+    ScopedLock<Semaphore> s(suspension);
+    if (session.get() && session->isAttached()) {
         session->detach();
         connection.broker.getSessionManager().suspend(session);
     }
diff --git a/cpp/src/qpid/broker/SessionHandler.h b/cpp/src/qpid/broker/SessionHandler.h
index 52f64779d4..800b886bbf 100644
--- a/cpp/src/qpid/broker/SessionHandler.h
+++ b/cpp/src/qpid/broker/SessionHandler.h
@@ -27,6 +27,8 @@
 #include "qpid/framing/AMQP_ClientProxy.h"
 #include "qpid/framing/amqp_types.h"
 #include "qpid/framing/ChannelHandler.h"
+#include "qpid/sys/Mutex.h"
+#include "qpid/sys/Semaphore.h"
 
 #include <boost/noncopyable.hpp>
 
@@ -94,6 +96,7 @@ class SessionHandler : public framing::FrameHandler::InOutHandler,
     bool ignoring;
     bool resuming;
     std::auto_ptr<SessionState> session;
+    sys::Semaphore suspension;
 };
 
 }} // namespace qpid::broker