diff --git a/lib/multithreading.c b/lib/multithreading.c
index fd3a5a5..2449f80 100644
--- a/lib/multithreading.c
+++ b/lib/multithreading.c
@@ -139,6 +139,9 @@ int iscsi_mt_sem_wait(libiscsi_sem_t* sem)
 
 #elif defined(HAVE_PTHREAD) /* WIN32 */
 
+#include <errno.h>
+#include <stdio.h>
+#include <signal.h>
 #include <unistd.h>
 #include <sys/syscall.h>
 
@@ -156,13 +159,20 @@ iscsi_tid_t iscsi_mt_get_tid(void)
 #endif
 }
 
+static void on_sigusr1(int _unused)
+{
+}
+
 static void *iscsi_mt_service_thread(void *arg)
 {
         struct iscsi_context *iscsi = (struct iscsi_context *)arg;
 	struct pollfd pfd;
 	int revents;
 	int ret;
-
+        
+        /* set signal to break poll when we need to send more data */
+        signal(SIGUSR1, on_sigusr1);
+        
         iscsi->multithreading_enabled = 1;
 
         /* TODO: add timeout scanning */
@@ -172,12 +182,21 @@ static void *iscsi_mt_service_thread(void *arg)
 		pfd.revents = 0;
         
 		ret = poll(&pfd, 1, iscsi->poll_timeout);
-		if (ret < 0) {
+                if (ret < 0 && errno == EINTR) {
+                        /*
+                         * Got a signal. Assume it is because we need to start writing new PDUs
+                         * to the socket.
+                         */
+                        revents = POLLOUT;
+                        goto call_service;
+                }
+                if (ret < 0) {
 			iscsi_set_error(iscsi, "Poll failed");
 			revents = -1;
 		} else {
 			revents = pfd.revents;
 		}
+        call_service:                
 		if (iscsi_service(iscsi, revents) < 0) {
 			if (revents != -1)
 				iscsi_set_error(iscsi, "iscsi_service failed");
diff --git a/lib/socket.c b/lib/socket.c
index f1a1e15..21f4ae3 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -62,6 +62,10 @@
 #include <sys/uio.h>
 #endif
 
+#ifdef HAVE_PTHREAD
+#include <signal.h>
+#endif
+
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -88,7 +92,7 @@ union socket_address {
 void
 iscsi_add_to_outqueue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 {
-	struct iscsi_pdu *current = iscsi->outqueue;
+	struct iscsi_pdu *current;
 	struct iscsi_pdu *last = NULL;
 
 	if (iscsi->scsi_timeout > 0) {
@@ -97,12 +101,15 @@ iscsi_add_to_outqueue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 		pdu->scsi_timeout = 0;
 	}
 
-	if (iscsi->outqueue == NULL) {
+        iscsi_mt_mutex_lock(&iscsi->iscsi_mutex);
+
+        current = iscsi->outqueue;
+        if (iscsi->outqueue == NULL) {
 		iscsi->outqueue = pdu;
 		pdu->next = NULL;
-		return;
+                goto finished;
 	}
-	
+        
 	/* queue pdus in ascending order of CmdSN. 
 	 * ensure that pakets with the same CmdSN are kept in FIFO order.
 	 * immediate PDUs are queued in front of queue with the CmdSN
@@ -131,7 +138,7 @@ iscsi_add_to_outqueue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 				iscsi->outqueue=pdu;
 			}
 			pdu->next = current;
-			return;
+                        goto finished;
 		}
 		last=current;
 		current=current->next;
@@ -139,9 +146,24 @@ iscsi_add_to_outqueue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 	
 	last->next = pdu;
 	pdu->next = NULL;
+
+ finished:
+        iscsi_mt_mutex_unlock(&iscsi->iscsi_mutex);
+
+        /* TODO QQQ need to immediately send for the non multithreading case too
+         * and for the Windows API too */
+#if defined(HAVE_MULTITHREADING) && defined(HAVE_PTHREAD)
+        if (current == NULL && pdu == iscsi->outqueue) {
+                if(iscsi->multithreading_enabled) {
+                        pthread_kill(iscsi->service_thread, SIGUSR1);
+                }
+        }
+#endif        
+        return;
 }
 
 void iscsi_decrement_iface_rr() {
+        /* TODO QQQ use an atomic here */
 	iface_rr--;
 }