postgresql/postgresql-oom-adj.patch

58 lines
2.0 KiB
Diff
Raw Normal View History

Back-ported patch from Postgres devel head: reset oom_adj to zero in any
postmaster child process. This allows us to disable OOM kill on the postmaster
(see the init script) without affecting OOM behavior for child processes.
diff -Naur postgresql-8.4.2.orig/src/backend/postmaster/fork_process.c postgresql-8.4.2/src/backend/postmaster/fork_process.c
--- postgresql-8.4.2.orig/src/backend/postmaster/fork_process.c 2009-01-01 12:23:46.000000000 -0500
+++ postgresql-8.4.2/src/backend/postmaster/fork_process.c 2010-01-11 12:28:17.000000000 -0500
@@ -12,7 +12,9 @@
#include "postgres.h"
#include "postmaster/fork_process.h"
+#include <fcntl.h>
#include <time.h>
+#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
@@ -60,6 +62,38 @@
setitimer(ITIMER_PROF, &prof_itimer, NULL);
#endif
+ /*
+ * By default, Linux tends to kill the postmaster in out-of-memory
+ * situations, because it blames the postmaster for the sum of child
+ * process sizes *including shared memory*. (This is unbelievably
+ * stupid, but the kernel hackers seem uninterested in improving it.)
+ * Therefore it's often a good idea to protect the postmaster by
+ * setting its oom_adj value negative (which has to be done in a
+ * root-owned startup script). If you just do that much, all child
+ * processes will also be protected against OOM kill, which might not
+ * be desirable. You can then choose to build with LINUX_OOM_ADJ
+ * #defined to 0, or some other value that you want child processes
+ * to adopt here.
+ */
+#ifdef LINUX_OOM_ADJ
+ {
+ /*
+ * Use open() not stdio, to ensure we control the open flags.
+ * Some Linux security environments reject anything but O_WRONLY.
+ */
+ int fd = open("/proc/self/oom_adj", O_WRONLY, 0);
+
+ /* We ignore all errors */
+ if (fd >= 0)
+ {
+ char buf[16];
+
+ snprintf(buf, sizeof(buf), "%d\n", LINUX_OOM_ADJ);
+ (void) write(fd, buf, strlen(buf));
+ close(fd);
+ }
+ }
+#endif /* LINUX_OOM_ADJ */
}
return result;