Perlbal::Manual::Debugging - Debugging Perlbal
DESCRIPTION
Perlbal has two ways of debugging.
One of them is through a management console; the other is through
debugging messages.
You'll need to set up a management service and use it to dump all
the information you require.
The comprehensive documentation on this process can be found at
Perlbal::Manual::Management.
You can control the ammount of debugging messages Perlbal dumps by
setting the environment variable
"PERLBAL_DEBUG" to a value between 0 and
4:
PERLBAL_DEBUG = 0 # no debug
PERLBAL_DEBUG = 4 # debug everything
Debug level 1
You can activate basic debug by setting
"PERLBAL_DEBUG" to 1:
PERLBAL_DEBUG = 1
The following debugging messages are turned on:
- When a connection to a backend is closed, Perlbal::BackendHTTP prints
"Backend $self is done; closing..."
- When a connection to a backend is killed, Perlbal::ClientProxy prints
"Client ($self) closing backend
($backend)"
- When an HTTP request fails to be parsed, Perlbal::HTTPHeaders prints
"HTTP parse failure: $reason"
- When the connection is promoted to SSL, Perlbal::TCPListener prints
" .. socket upgraded to SSL!"
Debug level 2
By setting the debug level to 2 you'll get all the messages from
level 1.
PERLBAL_DEBUG = 2
You will also get a few others:
- When a connection to a backend is opened and ready to be written to,
Perlbal::BackendHTTP prints "Backend $self is
writeable!"
- When a response is about to be handled, Perlbal::BackendHTTP prints
"BackendHTTP: handle_response"
- When a backend is ready to be read from, Perlbal::BackendHTTP prints
"Backend $self is readable!"
- When there's an error with the connection to the backend,
Perlbal::BackendHTTP prints "BACKEND
event_err"
- Whenever we're determining if we should be sending keep-alive header
information back to the client, Perlbal::ClientHTTPBase prints
"ClientHTTPBase::setup_keepalive($self)"
- Whenever the client is ready for more of its file, Perlbal::ClientHTTPBase
prints "REPROXY SSL done"
- Right after we've read a chunk of a file and when a reproxy request is
about to be sent, Perlbal::ClientHTTPBase prints
"REPROXY Sent: $sent"
- When we've written all data in the queue (and are about to stop waiting
for write notifications), Perlbal::ClientHTTPBase prints
"All writing done to $self"
- Whenever a client proxy is about to be closed, Perlbal::ClientProxy prints
"Perlbal::ClientProxy closed", followed
by a possible "again" and a possible
"saying $reason"
- When a client has disconnected, Perlbal::ClientProxy prints
"ClientProxy::client_disconnected"
- When a backend requests a client of a high priority request and the client
is available, "Service" in Perlbal prints
"Got from fast queue, in front of $backlog
others"
- When a backend requests a client of a normal priority request and the
client is available, "Service" in Perlbal prints
"Backend requesting client, got PRIORITY =
$cp-"{fd}.>
- When a backend requests a client of a low priority request and the client
is available, "Service" in Perlbal prints
"Backend requesting client, got low priority =
$cp-"{fd}.>
- When header are being read, Perlbal::Socket prints
"Perlbal::Socket::read_headers($self)
is_res=$is_res"
Debug level 3
PERLBAL_DEBUG = 3
By setting the debug level to 3 you'll get all the messages from
level 1 and 2 plus the following:
- Right before response headers are written to the client,
Perlbal::BackendHTTP prints " writing response
headers to client"
- As we're writing to the client, Perlbal::BackendHTTP prints
" content_length=VALUE" and
" remain=VALUE", where the values are
"undef" if they are not defined
- If we're done writing to the client, Perlbal::BackendHTTP prints
" done. detaching."
- Whenever we're determining if we should be sending keep-alive header
information back to the client, Perlbal::ClientHTTPBase prints
" service's persist_client =
$persist_client"
- While determining if we should be sending keep-alive header information
back to the client, if we were sent
"content-length" or it's a head request,
as we're doing a keep alive Perlbal::ClientHTTPBase prints
" doing keep-alive to client"
- If we're not sending keep-alive header information back ot the client,
Perlbal::ClientHTTPBase prints " doing connection:
close"
- Right after we've finished sending all of the results to the user,
Perlbal::ClientProxy prints
"ClientProxy::backend_finished"
- When we've sent a response to a user fully and we need to reset state,
Perlbal::ClientProxy prints
"ClientProxy::http_response_sent -- resetting
state"
- When we're writing a response to a client, Perlbal::ClientProxy prints
"ClientProxy::event_write"
- After writing a response to a client, if it is still connected and we're
triggering trigger our backend to keep reading, Perlbal::ClientProxy
prints " unstalling backend"
- When reading a request, Perlbal::ClientProxy prints
"ClientProxy::event_read"
- When reading a request and just before we read the headers,
Perlbal::ClientProxy prints " no headers.
reading."
- When reading a request, if we're not buffering to disk or we're no longer
reading, as we disable reads, Perlbal::ClientProxy prints
" disabling reads."
- As we're reading, Perlbal::ClientProxy prints "
reading $read_size bytes (VALUE bytes remain)", where
"VALUE bytes remain" can be
<undef>
- After each read, Perlbal::ClientProxy prints " read
$len bytes"
- After we finished reading the request, Perlbal::ClientProxy prints
" done_reading = $done_reading, backend =
BACKEND", where "BACKEND"
can be "undef"
- When we send the headers to the backend and it responds before we're done
reading from the client, further reads from the client are discarded; in
this situation Perlbal::ClientProxy prints " already
responded.". If the client continues to send data,
Perlbal::ClientProxy prints " already responded
[2]." and then gives up on reading
- After reading, and having a backend available where we can write to, just
before we do, Perlbal::ClientProxy prints " got a
backend. sending write to it."
- After reading, if there's no backend available, Perlbal::ClientProxy
prints " no backend. read_ahead =
$self-"{read_ahead}.>
- If we know we've already started spooling a file to disk and we're about
to continue doing so, Perlbal::ClientProxy prints "
bureason = $self-"{bureason}>
- If a backend wasn't available and we're about to request one,
Perlbal::ClientProxy prints " finally requesting a
backend"
- When we're trying to read headers and the client has disconnected,
Perlbal::Socket prints " client
disconnected"
- If we need to remove a trailing "\r\n"
from the headers, Perlbal::Socket prints " throwing
away leading \r\n"
- If we've read a packet with headers and by the end of it we can't find the
end of them, Perlbal::Socket prints " can't find end
of headers"
- Once we've read some headers, Perlbal::Socket prints
" pre-parsed headers: [$hstr]"
- After reading headers, if there's additional content that we've read, we
push it back; when we do so, Perlbal::Socket prints
" pushing back $len bytes after
header"
- If we got bogus headers, and right before we close the connection due to a
parsing failure, Perlbal::Socket prints " bogus
headers"
- If we got valid headers, Perlbal::Socket prints "
got valid headers"
- If we're reading buffered data from a client, Perlbal::Socket prints
"draining readbuf from $self to $dest:
[$$bref]"
Debug level 4
By setting the debug level to 4 you get all the messages from
levels 1 to 3.
Plus, "write" is redefined so
that whenever "write" is called it first
prints "write($self,
<$clen>"$content") from ($pkg, $filename,
$line)".
PERLBAL_DEBUG = 4
SEE ALSO
Perlbal::Manual::Configuration, Perlbal::Manual::Management.