if (obj.status == 503 && req.restarts < 4) {
restart;
}under vcl_error subroutine. It will rerequest the document however even with that behavior is still happening though much less :-(. I have attached some graphs of 500 responses from varnish and corresponding apache responses. Units are hits per second.
I even looked at corresponding responses from Apache and Apache would claim that the request succeeded yet varnish would throw a 500.
Vladimir On Tue, 30 Mar 2010, Justin Pasher wrote:
I'm currently running Varnish r4633 (I can upgrade if absolutely necessary), and we've been receiving very sporadic 503 errors listed in the log files generated by varnishncsa. It's a very small percentage, but nonetheless, when it happens on an important page, it's noticeable.Stats from yesterday's log file show 116 "503" errors out of about 4.1 million hits. About 80% of the failed requests are POST requests, which it setup in my VCL as a "pass through". If I look in the apache logs (the backend server), I only see one 503 error returned by apache itself, so maybe there's a timeout issue somewhere. I'm trying to figure out the best way to troubleshoot this, since it's too inconsistent to just sit watching the output of varnishlog.Perhaps it's hitting the default value for between_bytes_timeout (60 seconds)? If processing the data on the backend takes too long, then varnish would time out after 60 seconds of no data, even if the backend is still churning, right? I guess the question is what situations cause Varnish to return a 503 aside from when the backend itself returns a 503.I can post details of my VCL if needed, but it's pretty simple (mostly taken from examples on the site).
<<attachment: apache_500.png>>
<<attachment: varnish_500.png>>
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