Make pgbench use erand48() rather than random().

glibc renders random() thread-safe by wrapping a futex lock around it;
testing reveals that this limits the performance of pgbench on machines
with many CPU cores.  Rather than switching to random_r(), which is
only available on GNU systems and crashes unless you use undocumented
alchemy to initialize the random state properly, switch to our built-in
implementation of erand48(), which is both thread-safe and concurrent.

Since the list of reasons not to use the operating system's erand48()
is getting rather long, rename ours to pg_erand48() (and similarly
for our implementations of lrand48() and srand48()) and just always
use those.  We were already doing this on Cygwin anyway, and the
glibc implementation is not quite thread-safe, so pgbench wouldn't
be able to use that either.

Per discussion with Tom Lane.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/port/srandom.c b/src/port/srandom.c
index d70e3d855f6..8a25a21e926 100644
--- a/src/port/srandom.c
+++ b/src/port/srandom.c
@@ -21,5 +21,5 @@
 void
 srandom(unsigned int seed)
 {
-	srand48((long int) seed);
+	pg_srand48((long int) seed);
 }