Broken reload support?

[jeffkaufman]

In this ngx_pagespeed installation guide it notes:

please note that whenever you modify the PageSpeed configuration, no matter if in the main nginx configuration or in a vhost, you must restart nginx - a simple reload does not work

I wrote to the author, who said:

nginx does not seem to take care of Pagespeed configuration changes when I run
/etc/init.d/nginx reload
whereas
/etc/init.d/nginx restart
seems to work. I'm not sure if the reload is sending a HUP to nginx though.

[oschaaf]

Testing this, nginx -s reload indeed is broken. Not only isn't it working, it leaves the worker process unable to handle new requests. Sending a few more reloads that way eventually leads up to the a segfault.

Looking in to it.

[oschaaf]

The first thing I notice is that NgxRewriteOptions::Initialize() and NgxRewriteDriverFactory::Initialize() are called during the reload in the old worker process, which probably isn't going down well. I think I need to look at some older code, and check how this was wired back then. I remember reloading used to work fine.

[oschaaf]

The above happens when nginx.conf has disabled the use of a master process, in which case reloading isn't working at all. When configured to use a master process, reloading seems to be working most of the time - but I did manage to catch a segfault during a worker shutdown:

(gdb) bt
#0  0x0000000000000031 in ?? ()
#1  0x0000000000484ba9 in net_instaweb::RewriteDriverFactory::Deleter<net_instaweb::SerfUrlAsyncFetcher>::Run (
    this=<optimized out>) at ../ngx_pagespeed/psol/include/net/instaweb/rewriter/public/rewrite_driver_factory.h:475
#2  0x00000000006345d6 in net_instaweb::Function::CallRun (this=0x11cd150) at pagespeed/kernel/base/function.cc:51
#3  0x00000000004f65e9 in net_instaweb::RewriteDriverFactory::~RewriteDriverFactory (this=0x11c3980, 
    __in_chrg=<optimized out>) at net/instaweb/rewriter/rewrite_driver_factory.cc:147
#4  0x0000000000484a13 in ~SystemRewriteDriverFactory (this=0x11c3980, __in_chrg=<optimized out>)
    at ../ngx_pagespeed/psol/include/net/instaweb/system/public/system_rewrite_driver_factory.h:31
#5  net_instaweb::NgxRewriteDriverFactory::~NgxRewriteDriverFactory (this=0x11c3980, __in_chrg=<optimized out>)
    at ../ngx_pagespeed/src/ngx_rewrite_driver_factory.cc:111
#6  0x0000000000484abd in net_instaweb::NgxRewriteDriverFactory::~NgxRewriteDriverFactory (this=0x11c3980, 
    __in_chrg=<optimized out>) at ../ngx_pagespeed/src/ngx_rewrite_driver_factory.cc:117
#7  0x000000000047c287 in ngx_psol::(anonymous namespace)::ps_cleanup_srv_conf (data=<optimized out>)
    at ../ngx_pagespeed/src/ngx_pagespeed.cc:563
#8  0x000000000040e821 in ngx_destroy_pool (pool=0x11c8430) at src/core/ngx_palloc.c:55
#9  0x000000000042af07 in ngx_worker_process_exit (cycle=0x11c8480) at src/os/unix/ngx_process_cycle.c:1067
#10 0x000000000042b003 in ngx_worker_process_cycle (cycle=0x11c8480, data=<optimized out>)
    at src/os/unix/ngx_process_cycle.c:801
#11 0x00000000004297cb in ngx_spawn_process (cycle=0x11c8480, proc=0x42af3f <ngx_worker_process_cycle>, data=0x0, 
    name=0xbe8349 "worker process", respawn=-4) at src/os/unix/ngx_process.c:198
#12 0x000000000042a4d8 in ngx_start_worker_processes (cycle=0x11c8480, n=1, type=-4)
    at src/os/unix/ngx_process_cycle.c:362
#13 0x000000000042c074 in ngx_master_process_cycle (cycle=0x11c8480) at src/os/unix/ngx_process_cycle.c:249
#14 0x000000000040d718 in main (argc=<optimized out>, argv=<optimized out>) at src/core/nginx.c:412

[jeffkaufman]

Fixed by #439