random 503 + FetchError: straight insufficient bytes

[Nicolas Delmas]

Hello,

We are using Apache 2.4 on the backend and Varnish 4.1.2.

Randomly, users get 503 on some URL.
95% on time it's on an URL called by AJAX in POST method.:


-   BereqMethod    POST
-   BereqURL       /proxy.php?xdp_path=http%3A%2F%2Fmonsite.com%2Fcf_log.php

or it could be the same without a proxy.php


-   BereqMethod    POST
-   BereqURL       monsite.com/cf_log.php

With varnishlog I get this error :

*   << Request  >> 41189403-   FetchError     straight insufficient bytes

**  << BeReq    >> 41189404--  FetchError     req.body read error: 0 (Success)
--  FetchError     backend write error: 0 (Success)


*   << Request  >> 41189403-   FetchError     Connection reset by peer
-   FetchError     straight insufficient bytes
**  << BeReq    >> 41189404--  FetchError     req.body read error: 11
(Resource temporarily unavailable)
--  FetchError     backend write error: 11 (Resource temporarily unavailable)

I ran ngrep on Varnish an each time I get the error I have something like
this :

* client => varnish
>              header content [AP]
> *client => varnish
>              ..[AR]


and the data POST are not in the request

When all works I get something like this

* client => varnish

              header content[AP]

*client => varnish

             header content[AF]


And the last request contains the data POST.

How can I avoid to get this errors which seem to be false positive ?

Thank you



*Nicolas Delmas*
colas.delmas at gmail.com
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