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5cd4bbd7ab
The management of the servers and the proxies queues was not thread-safe at all. First, the accesses to <strm>->pend_pos were not protected. So it was possible to release it on a thread (for instance because the stream is released) and to use it in same time on another one (because we redispatch pending connections for a server). Then, the accesses to stream's information (flags and target) from anywhere is forbidden. To be safe, The stream's state must always be updated in the context of process_stream. So to fix these issues, the queue module has been refactored. A lock has been added in the pendconn structure. And now, when we try to dequeue a pending connection, we start by unlinking it from the server/proxy queue and we wake up the stream. Then, it is the stream reponsibility to really dequeue it (or release it). This way, we are sure that only the stream can create and release its <pend_pos> field. However, be careful. This new implementation should be thread-safe (hopefully...). But it is not optimal and in some situations, it could be really slower in multi-threaded mode than in single-threaded one. The problem is that, when we try to dequeue pending connections, we process it from the older one to the newer one independently to the thread's affinity. So we need to wait the other threads' wakeup to really process them. If threads are blocked in the poller, this will add a significant latency. This problem happens when maxconn values are very low. This patch must be backported in 1.8.
49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
/*
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include/types/queue.h
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This file defines variables and structures needed for queues.
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Copyright (C) 2000-2006 Willy Tarreau - w@1wt.eu
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation, version 2.1
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exclusively.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _TYPES_QUEUE_H
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#define _TYPES_QUEUE_H
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#include <common/config.h>
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#include <common/mini-clist.h>
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#include <common/hathreads.h>
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#include <types/server.h>
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struct stream;
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struct pendconn {
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int strm_flags; /* stream flags */
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struct stream *strm;
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struct proxy *px;
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struct server *srv; /* the server we are waiting for, may be NULL */
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struct list list; /* next pendconn */
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__decl_hathreads(HA_SPINLOCK_T lock);
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};
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#endif /* _TYPES_QUEUE_H */
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/*
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* Local variables:
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* c-indent-level: 8
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* c-basic-offset: 8
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* End:
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*/
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