varnish4 and http first read error

[Laurent Lavaud]

Hello,

I am using varnish 4.0.2 on a debian wheezy.

I have regularly a "http first read error: EOF", what can cause this type of error ?

All timeouts are at their default value, and if i curl the uri from the varnish server, it respond very quickly:

webcache27:~# curl -I -H 'Host: myhost' http://172.20.0.26/var/si-blocks/4e6c52943e611be51251e8f569f5a8c0.htm
HTTP/1.1 200 OK
Date: Wed, 26 Nov 2014 12:15:08 GMT
Server: Apache
Accept-Ranges: bytes
Cache-Control: public,max-age=120
Expires: Wed, 26 Nov 2014 12:16:08 GMT
Vary: Accept-Encoding
X-Server: webssi16
Edge-Control: public,max-age=120,!no-store
Content-Length: 12234
Content-Type: text/html


varnishlog output:

*4* << BeReq    >> 10586604
-4- Begin          bereq 10586603 bgfetch
-4- Timestamp      Start: 1417000330.684762 0.000000 0.000000
-4- BereqMethod    GET
-4- BereqURL       /var/si-blocks/4e6c52943e611be51251e8f569f5a8c0.htm
-4- BereqProtocol  HTTP/1.1
-4- BereqHeader    User-Agent: check_http/v1.4.16 (nagios-plugins 1.4.16)
-4- BereqHeader    Host: myhost
-4- BereqHeader    Surrogate-Capability: abc=ESI/1.0
-4- BereqHeader    X-Forwarded-For: 10.114.8.12, 10.114.8.12
-4- BereqHeader    Accept-Encoding: gzip
-4- BereqHeader    X-Varnish: 10586604
-4- VCL_call       BACKEND_FETCH
-4- BereqUnset     Accept-Encoding: gzip
-4- VCL_return     fetch
-4- BackendClose   41 webssi16(172.20.0.26,,80) toolate
-4- BackendOpen    41 webssi16(172.20.0.26,,80) 172.20.3.37 14224
-4- Backend        41 webssipool05 webssi16(172.20.0.26,,80)
-4- Timestamp      Bereq: 1417000330.685344 0.000582 0.000582
-4- FetchError     http first read error: EOF
-4- BackendClose   41 webssi16(172.20.0.26,,80)
-4- Timestamp      Beresp: 1417000330.699451 0.014689 0.014107
-4- Timestamp      Error: 1417000330.699461 0.014699 0.000010
-4- BerespProtocol HTTP/1.1
-4- BerespStatus   503
-4- BerespReason   Service Unavailable
-4- BerespReason   Backend fetch failed
-4- BerespHeader   Date: Wed, 26 Nov 2014 11:12:10 GMT
-4- BerespHeader   Server: Varnish
-4- VCL_call       BACKEND_ERROR
-4- BerespHeader   Content-Type: text/html; charset=utf-8
-4- BerespHeader   Retry-After: 30
-4- VCL_return     deliver
-4- Storage        malloc Transient
-4- ObjProtocol    HTTP/1.1
-4- ObjStatus      503
-4- ObjReason      Backend fetch failed
-4- ObjHeader      Date: Wed, 26 Nov 2014 11:12:10 GMT
-4- ObjHeader      Server: Varnish
-4- ObjHeader      Content-Type: text/html; charset=utf-8
-4- ObjHeader      Retry-After: 30
-4- Length         278
-4- BereqAcct      250 0 250 0 0 0
-4- End