07-30-2003
Hmmm....you do have a point. I was getting CBYTES mixed up with QBYTES.
I agree, for the most part, QNUM = 0 and CBYTES != 0 is not consistent. But I can think of one exception where it might make sense. When you do your msgsnd, you are setting msgflg to zero. That means that IPC_NOWAIT is turned off. The msgsnd system call checks to see if this message would exceed some limits. This includes a check of the message queue you are using as well as some system wide limits. If a msgsnd would exceed a limit and it did not set IPC_NOWAIT, the msgsnd system call will suspend until it is safe to send the message. I don't know what state the message queue is in during this suspension. It could well be that CBYTES has been increased but QNUM has not yet been incremented.
This would explain why it works for a few hours and then locks up. Reproduce the error and then run "ipcs -qa" and compare the total messages queue resources in use against your kernel parameters. If this is the problem, you will need to increase the kernel parameters. Or you may have a message queue leak somewhere.
That is my only idea. If it's not that, I would next suspect a broken kernel. You might check for any appropiate patches.
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LEARN ABOUT DEBIAN
stompserver
STOMPSERVER(1) User Commands STOMPSERVER(1)
NAME
stompserver - Stomp protocol messaging server
SYNOPSIS
stompserver [options]
DESCRIPTION
Stomp messaging server with file/dbm/memory/activerecord based FIFO queues, queue monitoring, and basic authentication.
OPTIONS
-C, --config=CONFIGFILE
Configuration File (default: stompserver.conf)
-p, --port=PORT
Change the port (default: 61613)
-b, --host=ADDR
Change the host (default: localhost)
-q, --queuetype=QUEUETYPE
Queue type (memory|dbm|activerecord|file) (default: memory)
-w, --working_dir=DIR
Change the working directory (default: current directory)
-s, --storage=DIR
Change the storage directory (default: .stompserver, relative to working_dir)
-d, --debug
Turn on debug messages
-a, --auth
Require client authorization
-c, --checkpoint=SECONDS
Time between checkpointing the queues in seconds (default: 0)
-h, --help
Show this message
QUEUES
Stompserver handles basic message queue processing using memory, file, or dbm based queues. Messages are sent and consumed in FIFO order
(unless a client error happens, this should be corrected in the future). Topics are memory-only storage. You can select activerecord, file
or dbm storage and the queues will use that, but topics will only be stored in memory.
memory queues are of course the fastest ones but shouldn't be used if you want to ensure all messages are delivered.
dbm queues will use berkeleydb if available, otherwise dbm or gdbm depending on the platform. sdbm does not work well with marshalled data.
Note that these queues have not been tested in this release.
For the file based storage, each frame is stored in a single file. The first 8 bytes contains the header length, the next 8 bytes contains
the body length, then the headers are stored as a marshalled object followed by the body stored as a string. This storage is currently
inefficient because queues are stored separately from messages, which forces a double write for data safety reasons on each message stored.
The activerecord based storage expects to find a database.yml file in the configuration directory. It should be the most robust backend,
but the slowest one. The database must have an ar_messages table which can be created with the following code (you are responsible to do
so):
ActiveRecord::Schema.define do
create_table 'ar_messages' do |t|
t.column 'stomp_id', :string, :null => false
t.column 'frame', :text, :null => false
end
end
You can read the frames with this model:
class ArMessage < ActiveRecord::Base
serialize :frame
end
The ar_message implementation will certainly change in the future.
This is meant to be easily readable by a Rails application (which could handle the ar_messages table creation with a migration).
ACCESS CONTROL
Basic client authorization is also supported. If the -a flag is passed to stompserver on startup, and a .passwd file exists in the run
directory, then clients will be required to provide a valid login and passcode. See passwd.example for the password file format.
MONITORING
Queues can be monitored via the monitor queue (this will probably not be supported this way in the future to avoid polluting the queue
namespace). If you subscribe to /queue/monitor, you will receive a status message every 5 seconds that displays each queue, it's size,
frames enqueued, and frames dequeued. Stats are sent in the same format of stomp headers, so they are easy to parse. Following is an exam-
ple of a status message containing stats for 2 queues:
Queue: /queue/client2 size: 0 dequeued: 400 enqueued: 400
Queue: /queue/test size: 50 dequeued: 250 enqueued: 300
AUTHOR
stompserver was written by Patrick Hurley <phurley@gmail.com> and Lionel Bouton.
This manual page was compiled from the included documentation by Bryan McLellan <btm@loftninjas.org> for the Debian project (and may be
used by others). The existing documentation is distributed under the MIT license.
stompserver July 2009 STOMPSERVER(1)