[trafficserver] branch 8.0.x updated: Throttling results in tight loop if there are no new connections

[vm...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

vmamidi pushed a commit to branch 8.0.x
in repository https://gitbox.apache.org/repos/asf/trafficserver.git


The following commit(s) were added to refs/heads/8.0.x by this push:
     new 1aa2150  Throttling results in tight loop if there are no new connections
1aa2150 is described below

commit 1aa215015d8bb13f3a106a06207184a376997f8b
Author: Vijay Mamidi <vi...@yahoo.com>
AuthorDate: Tue Apr 23 10:12:17 2019 +0800

    Throttling results in tight loop if there are no new connections
    
    (cherry picked from commit 1e9e4ed3be52dc8ef2433baba6816df4eb032055)
    
     Conflicts:
    	iocore/net/UnixNetAccept.cc
---
 iocore/net/UnixNetAccept.cc | 47 +++++++++------------------------------------
 1 file changed, 9 insertions(+), 38 deletions(-)

diff --git a/iocore/net/UnixNetAccept.cc b/iocore/net/UnixNetAccept.cc
index e494f5a..b5d80a7 100644
--- a/iocore/net/UnixNetAccept.cc
+++ b/iocore/net/UnixNetAccept.cc
@@ -41,29 +41,6 @@ safe_delay(int msec)
   socketManager.poll(nullptr, 0, msec);
 }
 
-static int
-drain_throttled_accepts(NetAccept *na)
-{
-  struct pollfd afd;
-  Connection con[THROTTLE_AT_ONCE];
-
-  afd.fd     = na->server.fd;
-  afd.events = POLLIN;
-
-  // Try to close at most THROTTLE_AT_ONCE accept requests
-  // Stop if there is nothing waiting
-  int n = 0;
-  for (; n < THROTTLE_AT_ONCE && socketManager.poll(&afd, 1, 0) > 0; n++) {
-    int res = 0;
-    if ((res = na->server.accept(&con[n])) < 0) {
-      return res;
-    }
-    con[n].close();
-  }
-  // Return the number of accept cases we closed
-  return n;
-}
-
 //
 // General case network connection accept code
 //
@@ -279,21 +256,7 @@ NetAccept::do_blocking_accept(EThread *t)
   // do-while for accepting all the connections
   // added by YTS Team, yamsat
   do {
-    ink_hrtime now = Thread::get_hrtime();
-
-    // Throttle accepts
-    while (!opt.backdoor && check_net_throttle(ACCEPT)) {
-      check_throttle_warning(ACCEPT);
-      int num_throttled = drain_throttled_accepts(this);
-      if (num_throttled < 0) {
-        goto Lerror;
-      }
-      NET_SUM_DYN_STAT(net_connections_throttled_in_stat, num_throttled);
-      now = Thread::get_hrtime();
-    }
-
     if ((res = server.accept(&con)) < 0) {
-    Lerror:
       int seriousness = accept_error_seriousness(res);
       if (seriousness >= 0) { // not so bad
         if (!seriousness) {   // bad enough to warn about
@@ -309,6 +272,14 @@ NetAccept::do_blocking_accept(EThread *t)
       }
       return -1;
     }
+    // check for throttle
+    if (!opt.backdoor && check_net_throttle(ACCEPT)) {
+      check_throttle_warning(ACCEPT);
+      // close the connection as we are in throttle state
+      con.close();
+      NET_SUM_DYN_STAT(net_connections_throttled_in_stat, 1);
+      continue;
+    }
 
     if (shutdown_event_system == true) {
       return -1;
@@ -324,7 +295,7 @@ NetAccept::do_blocking_accept(EThread *t)
     NET_SUM_GLOBAL_DYN_STAT(net_tcp_accept_stat, 1);
     vc->id = net_next_connection_number();
     vc->con.move(con);
-    vc->submit_time = now;
+    vc->submit_time = Thread::get_hrtime();
     vc->mutex       = new_ProxyMutex();
     vc->action_     = *action_;
     vc->set_is_transparent(opt.f_inbound_transparent);