[PATCH] readelf: Call __fsetlocking (stdout, FSETLOCKING_BYCALLER).

[PATCH] readelf: Call __fsetlocking (stdout, FSETLOCKING_BYCALLER).

[Mark Wielaard]

We only call printf on stdout from one thread, so we don't need internal
stdio locking for stdout.

On my machine eu-readelf -N --debug-dump=info libxul.so > /dev/null
goes from 65 seconds to 63 seconds.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 src/ChangeLog | 4 ++++
 src/readelf.c | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/src/ChangeLog b/src/ChangeLog
index cc12d83..19f4210 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2018-06-04  Mark Wielaard  <mark@klomp.org>
+
+	* readelf.c (main): Call __fsetlocking (stdout, FSETLOCKING_BYCALLER).
+
 2018-05-31  Mark Wielaard  <mark@klomp.org>
 
 	* readelf.c (print_debug_units): Print the dwo name and id when
diff --git a/src/readelf.c b/src/readelf.c
index 0725313..a578b27 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -35,6 +35,8 @@
 #include <locale.h>
 #include <stdarg.h>
 #include <stdbool.h>
+#include <stdio.h>
+#include <stdio_ext.h>
 #include <stdlib.h>
 #include <string.h>
 #include <strings.h>
@@ -310,6 +312,9 @@ static void dump_archive_index (Elf *, const char *);
 int
 main (int argc, char *argv[])
 {
+  /* We use no threads here which can interfere with handling a stream.  */
+  (void) __fsetlocking (stdout, FSETLOCKING_BYCALLER);
+
   /* Set locale.  */
   setlocale (LC_ALL, "");
 
-- 
1.8.3.1

Re: [PATCH] readelf: Call __fsetlocking (stdout, FSETLOCKING_BYCALLER).

[Mark Wielaard]

On Mon, Jun 04, 2018 at 06:54:53PM +0200, Mark Wielaard wrote:
> We only call printf on stdout from one thread, so we don't need internal
> stdio locking for stdout.
> 
> On my machine eu-readelf -N --debug-dump=info libxul.so > /dev/null
> goes from 65 seconds to 63 seconds.

Pushed to master.