Index: db.scm
==================================================================
--- db.scm
+++ db.scm
@@ -1409,11 +1409,14 @@
 	  (debug:print-info 7 "Received " response " from wrapped write")
 	  (server:reply return-address qry-sig response response))
 	;; otherwise if appropriate flush the queue (this is a read or complex query)
 	(begin
 	  (case *transport-type*
-	    ((http)(db:process-cached-writes db)))
+	    ((http)
+	  (mutex-lock! *db:process-queue-mutex*)
+	  (db:process-cached-writes db)
+	  (mutex-unlock! *db:process-queue-mutex*)))
 	  (cond
 	   ((member stmt-key db:special-queries)
 	    (debug:print-info 11 "Handling special statement " stmt-key)
 	    (case stmt-key
 	      ((immediate)

Index: server.scm
==================================================================
--- server.scm
+++ server.scm
@@ -66,11 +66,13 @@
 ;; has already been done?
 (define (server:write-queue-handler)
   (if (setup-for-run)
       (let ((db (open-db)))
 	(let loop ()
+	  (mutex-lock! *db:process-queue-mutex*)
 	  (db:process-cached-writes db)
+	  (mutex-unlock! *db:process-queue-mutex*)
 	  (thread-sleep! 0.3)
 	  (loop)))
       (begin
 	(debug:print 0 "ERROR: failed to setup for Megatest in server:write-queue-handler")
 	(exit 1))))