Force the TZ enviroment variable to be set, as this stops linux from …

…opening, calling fstat twice and reading /etc/localtime, giving a 2% boost to requests/second.

server/mpm/event/event.c

@@ -58,6 +58,7 @@
 #define APR_WANT_STRFUNC
 #include "apr_want.h"
 #include "apr_version.h"
+#include "apr_env.h"
 
 #if APR_HAVE_UNISTD_H
 #include <unistd.h>
@@ -2099,6 +2100,27 @@ static void join_start_thread(apr_thread_t * start_thread_id)
     }
 }
 
+static void force_set_tz(apr_pool_t *p) {
+    /* If the TZ variable is unset, many operationg systems,
+     * such as Linux, will at runtime read from /etc/localtime
+     * and call fstat on it.
+     *
+     * By forcing the time zone to UTC if it is unset, we gain
+     * about 2% in raw requests/second (since we format log files
+     * in the local time, if present)
+     *
+     * For more info, see:
+     *   <http://www.gnu.org/s/hello/manual/libc/TZ-Variable.html>
+     */
+    char *v = NULL;
+    apr_status_t rv;
+
+    rv = apr_env_get(&v, "TZ", p);
+    if (v == NULL || rv == APR_ENOENT) {
+        apr_env_set("TZ", "UTC+0", p);
+    }
+}
+
 static void child_main(int child_num_arg)
 {
     apr_thread_t **threads;
@@ -3143,6 +3165,8 @@ static void event_hooks(apr_pool_t * p)
     static const char *const aszSucc[] = { "core.c", NULL };
     one_process = 0;
 
+    force_set_tz(p);
+
     ap_hook_open_logs(event_open_logs, NULL, aszSucc, APR_HOOK_REALLY_FIRST);
     /* we need to set the MPM state before other pre-config hooks use MPM query
      * to retrieve it, so register as REALLY_FIRST