[core] improve logging when IPC blocking is detected

Throw a CRITical log with info on the target process

ipc.c

@@ -180,7 +180,7 @@ ipc_handler_type ipc_register_handler( ipc_handler_f *hdl, char *name)
 }
 
 
-static inline int __ipc_send_job(int fd, ipc_handler_type type,
+static inline int __ipc_send_job(int fd, int dst_proc, ipc_handler_type type,
 												void *payload1, void *payload2)
 {
 	ipc_job job;
@@ -202,33 +202,41 @@ static inline int __ipc_send_job(int fd, ipc_handler_type type,
 	 */
 	n = write(fd, &job, sizeof(job) );
 	if (n<0) {
-		if (errno==EINTR)
+		if (errno==EAGAIN || errno==EWOULDBLOCK)
+			LM_CRIT("blocking detected while sending job type %d[%s] on %d "
+				" to proc id %d/%d [%s]\n", type, ipc_handlers[type].name, fd,
+				dst_proc, (dst_proc==-1)?-1:pt[dst_proc].pid ,
+				(dst_proc==-1)?"n/a":pt[dst_proc].desc);
+		else if (errno==EINTR)
 			goto again;
-		LM_ERR("sending job type %d[%s] on %d failed: %s\n",
-			type, ipc_handlers[type].name, fd, strerror(errno));
+		else
+			LM_ERR("sending job type %d[%s] on %d failed: %s\n",
+				type, ipc_handlers[type].name, fd, strerror(errno));
 		return -1;
 	}
 	return 0;
 }
 
 int ipc_send_job(int dst_proc, ipc_handler_type type, void *payload)
 {
-	return __ipc_send_job(IPC_FD_WRITE(dst_proc), type, payload, NULL);
+	return __ipc_send_job(IPC_FD_WRITE(dst_proc), dst_proc,
+		type, payload, NULL);
 }
 
 int ipc_dispatch_job(ipc_handler_type type, void *payload)
 {
-	return __ipc_send_job(ipc_shared_pipe[1], type, payload, NULL);
+	return __ipc_send_job(ipc_shared_pipe[1], -1, type, payload, NULL);
 }
 
 int ipc_send_rpc(int dst_proc, ipc_rpc_f *rpc, void *param)
 {
-	return __ipc_send_job(IPC_FD_WRITE(dst_proc), ipc_rpc_type, rpc, param);
+	return __ipc_send_job(IPC_FD_WRITE(dst_proc), dst_proc,
+		ipc_rpc_type, rpc, param);
 }
 
 int ipc_dispatch_rpc( ipc_rpc_f *rpc, void *param)
 {
-	return __ipc_send_job(ipc_shared_pipe[1], ipc_rpc_type, rpc, param);
+	return __ipc_send_job(ipc_shared_pipe[1], -1, ipc_rpc_type, rpc, param);
 }
 
 int ipc_send_sync_reply(int dst_proc, void *param)