Shared memory logging
This document describes the format and content of all the Varnish shared memory logging tags. These tags are used by the varnishlog(1), varnishtop(1), etc. logging tools supplied with Varnish.
Backend - Backend selected
Logged when a connection is selected for handling a backend request.
The format is:
%d %s %s | | | | | +- Backend display name | +---- VCL name +------- Connection file descriptor
BackendClose - Backend connection closed
Logged when a backend connection is closed.
The format is:
%d %s [ %s ] | | | | | +- Optional reason | +------ Backend display name +--------- Connection file descriptor
BackendOpen - Backend connection opened
Logged when a new backend connection is opened.
The format is:
%d %s %s %s | | | | | | | +- Remote port | | +---- Remote address | +------- Backend display name +---------- Connection file descriptor
BackendReuse - Backend connection put up for reuse
Logged when a backend connection is put up for reuse by a later connection.
The format is:
%d %s | | | +- Backend display name +---- Connection file descriptor
Backend_health - Backend health check
The result of a backend health probe.
The format is:
%s %s %s %u %u %u %f %f %s | | | | | | | | | | | | | | | | | +- Probe HTTP response | | | | | | | +---- Average response time | | | | | | +------- Response time | | | | | +---------- Probe window size | | | | +------------- Probe threshold level | | | +---------------- Number of good probes in window | | +------------------- Probe window bits | +---------------------- Status message +------------------------- Backend name
Begin - Marks the start of a VXID
The first record of a VXID transaction.
The format is:
%s %d %s
| | |
| | +- Reason
| +---- Parent vxid
+------- Type ("sess", "req" or "bereq")
BereqAcct - Backend request accounting
Contains byte counters from backend request processing.
The format is:
%d %d %d %d %d %d | | | | | | | | | | | +- Total bytes received | | | | +---- Body bytes received | | | +------- Header bytes received | | +---------- Total bytes transmitted | +------------- Body bytes transmitted +---------------- Header bytes transmitted
BereqHeader - Backend request header
HTTP header contents.
The format is:
%s: %s | | | +- Header value +----- Header name
BereqMethod - Backend request method
The HTTP request method used.
BereqProtocol - Backend request protocol
The HTTP protocol version information.
BereqURL - Backend request URL
The HTTP request URL.
BerespHeader - Backend response header
HTTP header contents.
The format is:
%s: %s | | | +- Header value +----- Header name
BerespProtocol - Backend response protocol
The HTTP protocol version information.
BerespReason - Backend response response
The HTTP response string received.
BerespStatus - Backend response status
The HTTP status code received.
BogoHeader - Bogus HTTP received
Contains the first 20 characters of received HTTP headers we could not make sense of. Applies to both req.http and beresp.http.
CLI - CLI communication
CLI communication between varnishd master and child process.
Debug - Debug messages
Debug messages can normally be ignored, but are sometimes helpful during trouble-shooting. Most debug messages must be explicitly enabled with parameters.
ESI_BodyBytes - ESI body fragment byte counter
Contains the body byte count for this ESI body fragment. This number does not include any transfer encoding overhead.
The format is:
%d | +- Body bytes
ESI_xmlerror - ESI parser error or warning message
An error or warning was generated during parsing of an ESI object. The log record describes the problem encountered.
End - Marks the end of a VXID
The last record of a VXID transaction.
Error - Error messages
Error messages are stuff you probably want to know.
ExpBan - Object evicted due to ban
Logs the VXID when an object is banned.
ExpKill - Object expiry event
Logs events related to object expiry. The events are:
EXP_Rearm
Logged when the expiry time of an object changes.
EXP_Inbox
Logged when the expiry thread picks an object from the inbox for processing.
EXP_Kill
Logged when the expiry thread kills an object from the inbox.
EXP_When
Logged when the expiry thread moves an object on the binheap.
EXP_Expired
Logged when the expiry thread expires an object.
LRU_Cand
Logged when an object is evaluated for LRU force expiry.
LRU
Logged when an object is force expired due to LRU.
LRU_Fail
Logged when no suitable candidate object is found for LRU force expiry.
The format is:
EXP_Rearm p=%p E=%f e=%f f=0x%x EXP_Inbox p=%p e=%f f=0x%x EXP_Kill p=%p e=%f f=0x%x EXP_When p=%p e=%f f=0x%x EXP_Expired x=%u t=%f LRU_Cand p=%p f=0x%x r=%d LRU x=%u LRU_Fail Legend: p=%p Objcore pointer t=%f Remaining TTL (s) e=%f Expiry time (unix epoch) E=%f Old expiry time (unix epoch) f=0x%x Objcore flags r=%d Objcore refcount x=%u Object VXID
FetchError - Error while fetching object
Logs the error message of a failed fetch operation.
Fetch_Body - Body fetched from backend
Ready to fetch body from backend.
The format is:
%d (%s) %s | | | | | +---- 'stream' or '-' | +--------- Text description of body fetch mode +------------- Body fetch mode
Gzip - G(un)zip performed on object
A Gzip record is emitted for each instance of gzip or gunzip work performed. Worst case, an ESI transaction stored in gzip'ed objects but delivered gunziped, will run into many of these.
The format is:
%c %c %c %d %d %d %d %d | | | | | | | | | | | | | | | +- Bit length of compressed data | | | | | | +---- Bit location of 'last' bit | | | | | +------- Bit location of first deflate block | | | | +---------- Bytes output | | | +------------- Bytes input | | +---------------- 'E': ESI, '-': Plain object | +------------------- 'F': Fetch, 'D': Deliver +---------------------- 'G': Gzip, 'U': Gunzip, 'u': Gunzip-test
Examples:
U F E 182 159 80 80 1392 G F E 159 173 80 1304 1314
Hash - Value added to hash
This value was added to the object lookup hash.
NB: This log record is masked by default.
Hit - Hit object in cache
Object looked up in cache. Shows the VXID of the object.
HitPass - Hit for pass object in cache.
Hit-for-pass object looked up in cache. Shows the VXID of the hit-for-pass object.
HttpGarbage - Unparseable HTTP request
Logs the content of unparseable HTTP requests.
Length - Size of object body
Logs the size of a fetch object body.
Link - Links to a child VXID
Links this VXID to any child VXID it initiates.
The format is:
%s %d %s
| | |
| | +- Reason
| +---- Child vxid
+------- Child type ("req" or "bereq")
LostHeader - Failed attempt to set HTTP header
Logs the header name of a failed HTTP header operation due to resource exhaustion or configured limits.
ObjHeader - Object header
HTTP header contents.
The format is:
%s: %s | | | +- Header value +----- Header name
ObjProtocol - Object protocol
The HTTP protocol version information.
ObjReason - Object response
The HTTP response string received.
ObjStatus - Object status
The HTTP status code received.
PipeAcct - Pipe byte counts
Contains byte counters for pipe sessions.
The format is:
%d %d %d %d | | | | | | | +------- Piped bytes to client | | +---------- Piped bytes from client | +------------- Backend request headers +---------------- Client request headers
ReqAcct - Request handling byte counts
Contains byte counts for the request handling. This record is not logged for ESI sub-requests, but the sub-requests' response body count is added to the main request.
The format is:
%d %d %d %d %d %d | | | | | | | | | | | +- Total bytes transmitted | | | | +---- Body bytes transmitted | | | +------- Header bytes transmitted | | +---------- Total bytes received | +------------- Body bytes received +---------------- Header bytes received
ReqHeader - Client request header
HTTP header contents.
The format is:
%s: %s | | | +- Header value +----- Header name
ReqMethod - Client request method
The HTTP request method used.
ReqProtocol - Client request protocol
The HTTP protocol version information.
ReqStart - Client request start
Start of request processing. Logs the client IP address and port number.
The format is:
%s %s | | | +- Port number +---- IP address
ReqURL - Client request URL
The HTTP request URL.
RespHeader - Client response header
HTTP header contents.
The format is:
%s: %s | | | +- Header value +----- Header name
RespProtocol - Client response protocol
The HTTP protocol version information.
RespReason - Client response response
The HTTP response string received.
RespStatus - Client response status
The HTTP status code received.
SessClose - Client connection closed
SessionClose is the last record for any client connection.
The format is:
%s %f | | | +- How long the session was open +---- Why the connection closed
SessOpen - Client connection opened
The first record for a client connection, with the socket-endpoints of the connection.
The format is:
%s %d %s %s %s %d
| | | | | |
| | | | | +- File descriptor number
| | | | +---- Local TCP port ('-' if !$log_local_addr)
| | | +------- Local IPv4/6 address ('-' if !$log_local_addr)
| | +---------- Listen socket
| +------------- Client TCP socket
+---------------- Client IPv4/6 address
Storage - Where object is stored
Type and name of the storage backend the object is stored in.
The format is:
%s %s
| |
| +- Name of storage backend
+---- Type ("malloc", "file", "persistent" etc.)
TTL - TTL set on object
A TTL record is emitted whenever the ttl, grace or keep values for an object is set.
The format is:
%s %d %d %d %d %d [ %d %u %u ] | | | | | | | | | | | | | | | | | +- Max-Age from Cache-Control header | | | | | | | +---- Expires header | | | | | | +------- Date header | | | | | +------------ Age (incl Age: header value) | | | | +--------------- Reference time for TTL | | | +------------------ Keep | | +--------------------- Grace | +------------------------ TTL +--------------------------- "RFC" or "VCL"
The last four fields are only present in "RFC" headers.
Examples:
RFC 19 -1 -1 1312966109 4 0 0 23 VCL 10 -1 -1 1312966109 4 VCL 7 -1 -1 1312966111 6 VCL 7 120 -1 1312966111 6 VCL 7 120 3600 1312966111 6 VCL 12 120 3600 1312966113 8
Timestamp - Timing information
Contains timing information for the Varnish worker threads.
Time stamps are issued by Varnish on certain events, and show the absolute time of the event, the time spent since the start of the work unit, and the time spent since the last timestamp was logged. See vsl(7) for information about the individual timestamps.
The format is:
%s: %f %f %f | | | | | | | +- Time since last timestamp | | +---- Time since start of work unit | +------- Absolute time of event +----------- Event label
VCL_Error - VCL execution error message
Logs error messages generated during VCL execution.
VCL_Log - Log statement from VCL
User generated log messages insert from VCL through std.log()
VCL_acl - VSL ACL check results
Logs VCL ACL evaluation results.
VCL_call - VCL method called
Logs the VCL method name when a VCL method is called.
VCL_return - VCL method return value
Logs the VCL method terminating statement.
VCL_trace - VCL trace data
Logs VCL execution trace data.
The format is:
%u %u.%u | | | | | +- VCL program line position | +---- VCL program line number +------- VCL trace point index
NB: This log record is masked by default.
VSL - VSL API warnings and error message
Warnings and error messages genererated by the VSL API while reading the shared memory log.
WorkThread - Logs thread start/stop events
Logs worker thread creation and termination events.
The format is:
%p %s | | | +- [start|end] +---- Worker struct pointer
NB: This log record is masked by default.
Timestamps are inserted in the log on completing certain events during the worker thread's task handling. The timestamps has a label showing which event was completed. The reported fields show the absolute time of the event, the time spent since the start of the task and the time spent since the last timestamp was logged.
The timestamps logged automatically by Varnish are inserted after completing events that are expected to have delays (e.g. network IO or spending time on a waitinglist). Timestamps can also be inserted from VCL using the std.timestamp() method. If one is doing time consuming tasks in the VCL configuration, it's a good idea to log a timestamp after completing that task. This keeps the timing information in subsequent timestamps from including the time spent on the VCL event.
Start
The start of request processing (first byte received or restart).
Req
Complete client request received.
ReqBody
Client request body processed (discarded, cached or passed to the backend).
Waitinglist
Came off waitinglist.
Fetch
Fetch processing finished (completely fetched or ready for streaming).
Process
Processing finished, ready to deliver the client response.
Resp
Delivery of response to the client finished.
Restart
Client request is being restarted.
Pipe
Opened a pipe to the backend and forwarded the request.
PipeSess
The pipe session has finished.
Start
Start of the backend fetch processing.
Bereq
Backend request sent.
Beresp
Backend response headers received.
BerespBody
Backend response body received.
Retry
Backend request is being retried.
Error
Backend request failed to vcl_backend_error.
This document was initially written by Poul-Henning Kamp, and later updated by Martin Blix Grydeland.