rq v0.1.7


rq (queue | export RQ_Q=q) mode [mode_args]* [options]*


rq is an tool used to create instant linux clusters by managing nfs
mounted priority work queues.  multiple instances of rq running from
multiples hosts can work from these queues to distribute processing load to n
nodes - bringing many dozens of otherwise powerful cpus to their knees with a
single blow.  clearly this software should be kept out of the hands of free
radicals, seti enthusiasts, and one mr. j. safran.

the central concept of rq is that n nodes work in isolation to pull
jobs from an central nfs mounted work priority work queue in a synchronized
fashion.  the nodes have absolutely no knowledge of each other and all
communication if done via the queue meaning that, so long as the queue is
available via nfs and a single node is running jobs from it, the system will
continue to process jobs.  there is no centralized process whatsoever - all
nodes work to take jobs from the queue and run them as fast as possible.  this
creates a system which load balances automatically and is robust in face of
node failures.

the first argument to any rq command is the name of the queue.  this
name may be omitted if, and only if, the environment variable RQ_Q has been
set to contain the absolute path of target queue.

rq operates in one of the modes create, submit, list, status,
delete, update, query, execute, configure, snapshot, lock, backup, help, or
feed.  depending on the mode of operation and the options used the meaning of
'mode_args' may change.


the following mode abbreviations exist

  c  => create
  s  => submit
  l  => list
  ls => list
  t  => status
  d  => delete
  rm => delete
  u  => update
  q  => query
  e  => execute
  C  => configure
  S  => snapshot
  L  => lock
  b  => backup
  h  => help
  f  => feed

create, c :

  create a queue.  the queue must be located on an nfs mounted file system
  visible from all nodes intended to run jobs from it.

  examples :

    0) to create a queue
        ~ > rq /path/to/nfs/mounted/q create
      or simply
        ~ > rq /path/to/nfs/mounted/q c

submit, s :

  submit jobs to a queue to be proccesed by a feeding node.  any 'mode_args'
  are taken as the command to run.  note that 'mode_args' are subject to shell
  expansion - if you don't understand what this means do not use this feature
  and pass jobs on stdin.

  when running in submit mode a file may by specified as a list of commands to
  run using the '--infile, -i' option.  this file is taken to be a newline
  separated list of commands to submit, blank lines and comments (#) are
  allowed.  if submitting a large number of jobs the input file method is
  MUCH, more efficient.  if no commands are specified on the command line rq 
  automatically reads them from STDIN.  yaml formatted files are also allowed
  as input ( - note that the output of nearly all rq 
  commands is valid yaml and may, therefore, be piped as input into the submit

  when submitting the '--priority, -p' option can be used here to determine
  the priority of jobs.  priorities may be any whole number - zero is the
  default.  note that submission of a high priority job will NOT supplant
  currently running low priority jobs, but higher priority jobs WILL always
  migrate above lower priority jobs in the queue in order that they be run as
  soon as possible.  constant submission of high priority jobs may create a
  starvation situation whereby low priority jobs are never allowed to run.
  avoiding this situation is the responsibility of the user.  the only
  guaruntee rq makes regarding job execution is that jobs are
  executed in an 'oldest highest priority' order and that running jobs are
  never supplanted.

  examples :

    0) submit the job ls to run on some feeding host

      ~ > rq q s ls

    1) submit the job ls to run on some feeding host, at priority 9

      ~ > rq -p9 q s ls 

    2) submit 42000 jobs (quietly) from a command file.

      ~ > wc -l cmdfile 
      ~ > rq q s -q < cmdfile

    3) submit 42 priority 9 jobs from a command file.

      ~ > wc -l cmdfile 
      ~ > rq -p9 q s < cmdfile

    4) submit 42 priority 9 jobs from a command file, marking them as
       'important' using the '--tag, -t' option.

      ~ > wc -l cmdfile 
      ~ > rq -p9 -timportant q s < cmdfile

    5) re-submit all the 'important' jobs (see 'query' section below)

      ~ > rq q query tag=important | rq q s

    6) re-submit all jobs which are already finished (see 'list' section

      ~ > rq q l f | rq q s 

list, l, ls :

  list mode lists jobs of a certain state or job id.  state may be one of
  pending, running, finished, dead, or all.  any 'mode_args' that are numbers
  are taken to be job id's to list.

  states may be abbreviated to uniqueness, therefore the following shortcuts
  apply :        

    p => pending
    r => running
    f => finished
    d => dead
    a => all

  examples :

    0) show everything in q
        ~ > rq q list all
        ~ > rq q l all
        ~ > export RQ_Q=q 
        ~ > rq l

    1) show q's pending jobs
        ~ > rq q list pending

    2) show q's running jobs
        ~ > rq q list running 

    3) show q's finished jobs
        ~ > rq q list finshed 

    4) show job id 42 
        ~ > rq q l 42 

status, t :

  status mode shows the global state the queue.  there are no 'mode_args'.
  the meaning of each state is as follows:

    pending  => no feeder has yet taken this job
    running  => a feeder has taken this job
    finished => a feeder has finished this job
    dead     => rq died while running a job, has restarted, and moved
                this job to the dead state

  note that rq cannot move jobs into the dead state unless it has
  been restarted.  this is because no node has any knowledge of other nodes
  and cannot possibly know if a job was started on a node that died, or is
  simply taking a very long time.  only the node that dies, upon restart, can
  determine that is has jobs that 'were started before it started' and move
  these jobs into the dead state.  normally only a machine crash would cause a
  job to be placed into the dead state.  dead jobs are never automatically
  restarted, this is the responsibility of an operator.

  examples :

    0) show q's status

      ~ > rq q t 

delete, d :

  delete combinations of pending, running, finished, dead, or jobs specified
  by jid.  the delete mode is capable of parsing the output of list and query
  modes, making it possible to create custom filters to delete jobs meeting
  very specific conditions.

  'mode_args' are the same as for list.  note that while it is possible to
  delete a running job, but there is no way to actually STOP it mid execution
  since the node doing the deleteing has no way to communicate this
  information to the (probably) remote execution node.  therefore you should
  use the 'delete running' feature with care and only for housekeeping
  purposes or to prevent future jobs from being scheduled.

  examples :

    0) delete all pending, running, and finished jobs from a queue

      ~ > rq q d all

    1) delete all pending jobs from a queue

      ~ > rq q d p 

    2) delete all finished jobs from a queue

      ~ > rq q d f 

    3) delete jobs via hand crafted filter program

      ~ > rq q list | yaml_filter_prog | rq q d

update, u :

  update assumes all leading arguments are jids to update with subsequent
  key=value pairs.  currently only the 'command', 'priority', and 'tag' fields
  of pending jobs can be updated.


    0) update the priority of job 42 

      ~ > rq q update 42 priority=7 

    1) update the priority of all pending jobs 

      ~ > rq q update pending priority=7 

    2) query jobs with a command matching 'foobar' and update their command 
       to be 'barfoo'

      ~ > rq q q "command like '%foobar%'" |\
          rq q u command=barfoo 

query, q :

  query exposes the database more directly the user, evaluating the where
  clause specified on the command line (or from STDIN).  this feature can be
  used to make a fine grained slection of jobs for reporting or as input into
  the delete command.  you must have a basic understanding of SQL syntax to
  use this feature, but it is fairly intuitive in this limited capacity.


    0) show all jobs submitted within a specific 10 minute range

      ~ > rq q query "started >= '2004-06-29 22:51:00' and started < '2004-06-29 22:51:10'"

    1) shell quoting can be tricky here so input on STDIN is also allowed to
       avoid shell expansion

      ~ > cat constraints.txt 
      started >= '2004-06-29 22:51:00' and
      started < '2004-06-29 22:51:10'

      ~ > rq q query < contraints.txt
        or (same thing)

      ~ > cat contraints.txt| rq q query

      ** in general all but numbers will need to be surrounded by single quotes **

    2) this query output might then be used to delete those jobs

      ~ > cat contraints.txt | rq q q | rq q d

    3) show all jobs which are either finished or dead 

      ~ > rq q q "state='finished' or state='dead'"

    4) show all jobs which have non-zero exit status

      ~ > rq q query exit_status!=0 

    5) if you plan to query groups of jobs with some common feature consider
       using the '--tag, -t' feature of the submit mode which allows a user to
       tag a job with a user defined string which can then be used to easily
       query that job group 

      ~ > rq q submit --tag=my_jobs < joblist 
      ~ > rq q query tag=my_jobs 

execute, e :

  execute mode is to be used by expert users with a knowledge of sql syntax
  only.  it follows the locking protocol used by rq and then allows
  the user to execute arbitrary sql on the queue.  unlike query mode a write
  lock on the queue is obtained allowing a user to definitively shoot
  themselves in the foot.  for details on a queue's schema the file
  'db.schema' in the queue directory should be examined.

    examples :

      0) list all jobs

        ~ > rq q execute 'select * from jobs'

configure, C :

  this mode is not supported yet.

snapshot, p :

  snapshot provides a means of taking a snapshot of the q. use this feature
  when many queries are going to be run; for example when attempting to figure
  out a complex pipeline command your test queries will not compete with the
  feeders for the queue's lock.  you should use this option whenever possible
  to avoid lock competition.


    0) take a snapshot using default snapshot naming, which is made via the
       basename of the q plus '.snapshot'

      ~ > rq /path/to/nfs/q snapshot 

    1) use this snapshot to chceck status

      ~ > rq ./q.snapshot status 

    2) use the snapshot to see what's running on which host

      ~ > rq ./q.snapshot list running | grep `hostname` 

  note that there is also a snapshot option - this option is not the same as
  the snapshot command.  the option can be applied to ANY command. if in
  effect then that command will be run on a snapshot of the database and the
  snapshot then immediately deleted.  this is really only useful if one were
  to need to run a command against a very heavily loaded queue and did not
  wish to wait to obtain the lock.  eg.

    0) get the status of a heavily loaded queue

      ~ > rq q t --snapshot

    1) same as above 

      ~ > rq q t -s

lock, L :

  lock the queue and then execute an arbitrary shell command.  lock mode uses
  the queue's locking protocol to safely obtain a lock of the specified type
  and execute a command on the user's behalf.  lock type must be one of

    (r)ead | (sh)ared | (w)rite | (ex)clusive

  examples :

    0) get a read lock on the queue and make a backup

      ~ > rq q L read -- cp -r q q.bak

      (the '--' is needed to tell rq to stop parsing command line
       options which allows the '-r' to be passed to the 'cp' command)

backup, b :

  backup mode is exactly the same as getting a read lock on the queue and
  making a copy of it.  this mode is provided as a convenience.

    0) make a backup of the queue using default naming ( qname + timestamp + .bak )

      ~ > rq q b

    1) make a backup of the queue as 'q.bak' 

      ~ > rq q b q.bak

help, h :

  this message

  examples :

    0) get this message

      ~> rq q help
      ~> rq help

feed, f :

  take jobs from the queue and run them on behalf of the submitter as quickly
  as possible.  jobs are taken from the queue in an 'oldest highest priority'
  first order.  

  feeders can be run from any number of nodes allowing you to harness the CPU
  power of many nodes simoultaneously in order to more effectively clobber
  your network, anoy your sysads, and set output raids on fire.

  the most useful method of feeding from a queue is to do so in daemon mode so
  that if the process loses it's controling terminal it will not exit when you
  exit your terminal session.  use the '--daemon, -d' option to accomplish
  this.  by default only one feeding process per host per queue is allowed to
  run at any given moment.  because of this it is acceptable to start a feeder
  at some regular interval from a cron entry since, if a feeder is alreay
  running, the process will simply exit and otherwise a new feeder will be
  started.  in this way you may keep feeder processing running even acroess
  machine reboots without requiring sysad intervention to add an entry to the
  machine's startup tasks.

  examples :

    0) feed from a queue verbosely for debugging purposes, using a minimum and
       maximum polling time of 2 and 4 respectively.  you would NEVER specify
       polling times this brief except for debugging purposes!!!

      ~ > rq q feed -v4 -m2 -M4

    1) same as above, but viewing the executed sql as it is sent to the

      ~ > RQ_SQL_DEBUG=1 rq q f -v4 -m2 -M4

    2) feed from a queue in daemon mode - logging to /home/ahoward/rq.log

      ~ > rq q f -d -l/home/ahoward/rq.log

       log rolling in daemon mode is automatic so your logs should never need
       to be deleted to prevent disk overflow.

    3) use something like this sample crontab entry to keep a feeder running
       forever - it attempts to (re)start every fifteen minutes but exits if
       another process is already feeding.

      # your crontab file - sample only

      */15 * * * * /full/path/to/bin/rq /full/path/to/nfs/mounted/q f -d -l/home/username/cfq.log -q

      the '--quiet, -q' here tells rq to exit quietly (no STDERR)
      when another process is found to already be feeding so that no cron
      message would be sent under these conditions.


- realize that your job is going to be running on a remote host and this has
  implications.  paths, for example, should be absolute, not relative.
  specifically the submitted job script must be visible from all hosts
  currently feeding from a queue as must be the input and output

- jobs are currently run under the bash shell using the --login option.
  therefore any settings in your .bashrc will apply - specifically your PATH
  setting.  you should not, however, rely on jobs running with any given

- you need to consider __CAREFULLY__ what the ramifications of having multiple
  instances of your program all potentially running at the same time will be.
  for instance, it is beyond the scope of rq to ensure multiple
  instances of a given program will not overwrite each others output files.
  coordination of programs is left entirely to the user.

- the list of finished jobs will grow without bound unless you sometimes
  delete some (all) of them.  the reason for this is that rq cannot
  know when the user has collected the exit_status of a given job, and so
  keeps this information in the queue forever until instructed to delete it.
  if you have collected the exit_status of you job(s) it is not an error to
  then delete that job from the finished list - the information is kept for
  your informational purposes only.  in a production system it would be normal
  to periodically save, and then delete, all finished jobs.


RQ_Q: set to the full path of nfs mounted queue

  the queue argument to all commands may be omitted if, and only if, the
  environment variable 'RQ_Q' contains the full path to the q.  eg.

    ~ > export RQ_Q=/full/path/to/my/q

  this feature can save a considerable amount of typing for those weak of


success : $? == 0
failure : $? != 0



0 < bugno && bugno <= 42

reports to


--priority=priority, -p 
      modes <submit> : set the job(s) priority - lowest(0) .. highest(n) - 
      (default 0) 
--tag=tag, -t 
      modes <submit> : set the job(s) user data tag 
--infile=infile, -i 
      modes <submit> : infile 
--quiet, -q 
      modes <submit, feed> : do not echo submitted jobs, fail silently if 
      another process is already feeding 
--daemon, -d 
      modes <feed> : spawn a daemon 
--max_feed=max_feed, -f 
      modes <feed> : the maximum number of concurrent jobs run 
--retries=retries, -r 
      modes <feed> : specify transaction retries 
--min_sleep=min_sleep, -m 
      modes <feed> : specify min sleep 
--max_sleep=max_sleep, -M 
      modes <feed> : specify max sleep 
--snapshot, -s 
      operate on snapshot of queue 
--verbosity=verbostiy, -v 
      0|fatal < 1|error < 2|warn < 3|info < 4|debug - (default info) 
--log=path, -l 
      set log file - (default stderr) 
      daily | weekly | monthly - what age will cause log rolling (default 
      size in bytes - what size will cause log rolling (default nil) 
--help, -h 
      this message