From 291a82f748de56e65fac10edefc51ec7a54a82d4 Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sat, 4 Aug 2018 20:38:48 +0000
Subject: [PATCH] thread.c (consume_communication_pipe): do not retry after
 short read

Saves a syscall and slightly improves vm_thread_condvar1
benchmark slightly (more improvements on the way):

                         r64170        this patch
vm_thread_condvar1        0.917        1.065

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64185 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 thread.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/thread.c b/thread.c
index 161f16365c..9c7fcee05f 100644
--- a/thread.c
+++ b/thread.c
@@ -4273,6 +4273,9 @@ consume_communication_pipe(int fd)
 	result = read(fd, buff, sizeof(buff));
 	if (result > 0) {
 	    ret = TRUE;
+	    if (result < (ssize_t)sizeof(buff)) {
+		return ret;
+	    }
 	}
 	else if (result == 0) {
 	    return ret;