#258: [PATCH] client spins on write when window full
--------------------+--------------------
Reporter: ncm | Owner:
Type: defect | Status: new
Priority: normal | Milestone: 1.4.3
Component: misc | Version: 1.4.2
Keywords: | Blocked By:
Blocks: |
--------------------+--------------------
I see CPU go to 100% on writes when the receiver is slow or slow to
deliver window adjustments. When the window appears to be full, it
seems a grave error to sleep on writability of a socket that is
writable all the time.
Suggesting this to reduce sender CPU load without reducing throughput:
{{{
--- a/src/channel.c
+++ b/src/channel.c
@@ -2012,9 +2012,17 @@ _libssh2_channel_write(LIBSSH2_CHANNEL *channel,
int stream_id,
if((rc < 0) && (rc != LIBSSH2_ERROR_EAGAIN))
return rc;
- if(channel->local.window_size <= 0)
- /* there's no room for data so we stop */
+ if(channel->local.window_size <= 0) {
+ /* there's no room for data so we stop. */
+
+ /* Waiting on the socket to be writable would be wrong
+ * because we would be back here immediately, but a readable
+ * socket might herald an incoming window adjustment.
+ */
+ session->socket_block_directions =
LIBSSH2_SESSION_BLOCK_INBOUND;
+
return (rc==LIBSSH2_ERROR_EAGAIN?rc:0);
+ }
channel->write_bufwrite = buflen;
}}}
--
Ticket URL: <https://trac.libssh2.org/ticket/258>
libssh2 <https://trac.libssh2.org/>
C library for writing portable SSH2 clients
_______________________________________________
libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
