--- file_not_specified_in_diff	
+++ file_not_specified_in_diff	
@@ -, +, @@ 
--- httpd-2.4.2/modules/proxy/mod_proxy_balancer.c
+++ httpd-2.4.2/modules/proxy/mod_proxy_balancer.c
@@ -825,6 +825,16 @@ 
                 proxy_worker_shared *shm;
 
                 worker = *workers;
+
+                /* Ckeck if we grabbed already */
+                if (storage->dptr(balancer->wslot, worker->s->index, (void *)&shm) == APR_SUCCESS) {
+                    if (shm == worker->s) {
+                        /* worker->s pointed to some shm before */
+                        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(05561) "won't grab worker-SHM %lu with index %d twice", (unsigned long int)(worker->s), worker->s->index);
+                        continue;
+                    }
+                }
+
                 if ((rv = storage->grab(balancer->wslot, &index)) != APR_SUCCESS) {
                     ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01186) "worker slotmem_grab failed");
                     return !OK;