Mercurial > hg > nginx
view src/event/ngx_event_posted.c @ 7969:84c60a3cd12a stable-1.20
Changed ngx_chain_update_chains() to test tag first (ticket #2248).
Without this change, aio used with HTTP/2 can result in connection hang,
as observed with "aio threads; aio_write on;" and proxying (ticket #2248).
The problem is that HTTP/2 updates buffers outside of the output filters
(notably, marks them as sent), and then posts a write event to call
output filters. If a filter does not call the next one for some reason
(for example, because of an AIO operation in progress), this might
result in a state when the owner of a buffer already called
ngx_chain_update_chains() and can reuse the buffer, while the same buffer
is still sitting in the busy chain of some other filter.
In the particular case a buffer was sitting in output chain's ctx->busy,
and was reused by event pipe. Output chain's ctx->busy was permanently
blocked by it, and this resulted in connection hang.
Fix is to change ngx_chain_update_chains() to skip buffers from other
modules unconditionally, without trying to wait for these buffers to
become empty.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Sat, 30 Oct 2021 02:39:19 +0300 |
parents | f1720934c45b |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> ngx_queue_t ngx_posted_accept_events; ngx_queue_t ngx_posted_next_events; ngx_queue_t ngx_posted_events; void ngx_event_process_posted(ngx_cycle_t *cycle, ngx_queue_t *posted) { ngx_queue_t *q; ngx_event_t *ev; while (!ngx_queue_empty(posted)) { q = ngx_queue_head(posted); ev = ngx_queue_data(q, ngx_event_t, queue); ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "posted event %p", ev); ngx_delete_posted_event(ev); ev->handler(ev); } } void ngx_event_move_posted_next(ngx_cycle_t *cycle) { ngx_queue_t *q; ngx_event_t *ev; for (q = ngx_queue_head(&ngx_posted_next_events); q != ngx_queue_sentinel(&ngx_posted_next_events); q = ngx_queue_next(q)) { ev = ngx_queue_data(q, ngx_event_t, queue); ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "posted next event %p", ev); ev->ready = 1; ev->available = -1; } ngx_queue_add(&ngx_posted_events, &ngx_posted_next_events); ngx_queue_init(&ngx_posted_next_events); }