| Version 10 (modified by , 13 years ago) ( diff ) |
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Shepherding the postage stamp server and the update process
Overview
Postage stamp request files are fits tables that contain 1 or more request specifications. Request files are submitted to the system five ways.
- By posting to a fileset on a data store that the server is monitoring
- by uploading a request file to the upload page.
- By entering a request on the PSI form
- by entering a "valid" set of parameters on the prototype web interface
- adding the request into the database with pstamptool -addreq -uri /request_file_path -label some label
Each file is represented in the database by a row in the table pstampRequest. The request starts life in state 'new'. Once it is done parsing the state is set to 'run'. Request files are parsed into jobs by the task pstamp.job.run. The working directory for a request is /data/ippc30.1/pstamp/work/$yyyy/$mm/$dd/$req_id. (Dates are UTC)
For example here is the entry for a request while it is being parsed
mysql> select * from pstampRequest where req_id = 5977; +--------+-------+-------+------------------+---------+--------+---------------+---------------------------------------------------------+-------------------------------------------+-------+ | req_id | ds_id | state | name | reqType | label | outProduct | uri | outdir | fault | +--------+-------+-------+------------------+---------+--------+---------------+---------------------------------------------------------+-------------------------------------------+-------+ | 5977 | 0 | new | Niall.1274580688 | pstamp | WEB.UP | pstampresults | /data/ippdb02.0/pstamp/work/20100527/5977/web_1695.fits | /data/ippdb02.0/pstamp/work/20100527/5977 | 0 | +--------+-------+-------+------------------+---------+--------+---------------+---------------------------------------------------------+-------------------------------------------+-------+ 1 row in set (0.00 sec)
Each row in the request table contains a request specification. Each row causes one or more pstampJobs to be entered into the database. Jobs are often entered with state = 'stop' and fault > 10. These are due to requests for images that can not be satisfied. The set of errors is listed at the bottom of this page.
Once the request table has completed parsing successfully it's state is set to 'run'. Once the request is in state run its jobs are eligible to run and will be output by pstamptool -pendingjob
If a pstampJob's input images have been cleaned a pstampDependent object is entered into the database with state 'new'. The pstampJob will not be run until it's dependent is set to 'full'.
The task pstamp.dependent.run runs the script pstamp_checkdependent.pl. This script queries the gpc1 database for the state of the dependent component. This script's job is to queue and monitor update processing for the dependent component. CAREFUL. THERE BE SPIDERS!
The log file for the dependent is stored in the file named "$pstampDependent->{outdir}/checkdep.$dep_id.log". The script runs periodically, the log file is appended to each time. The outdir for the dependent is the outdir of the first request that needs the component.
Once all jobs have completed (changed from run to stop state) the request is queued for "finishing". The task pstamp.finish.run builds the results fits table and packages up all of the data into a fileset on the request's outgoing data store.
Monitoring
The current workload can be seen at http://pstamp.ipp.ifa.hawaii.edu/status.php
Since the postage stamp / data store database is on ippc17 and not ippdb01 some care must be taken when running commands.
I define the environment variable PSDBSERVER=ippc17 and the alias
alias pst 'pstamptool -dbname ippRequestServer -dbserver $PSDBSERVER'
I always type pst instead of pstamptool. Since the postage stamp tables on gpc1 database have been dropped you get errors if you try and run pstamptool without -dbserver
(ipp032:~) bills% pstamptool -pendingreq
p_psDBRunQuery (psDB.c:812) : Failed to execute SQL query. Error: Table 'gpc1.pstampRequest' doesn't exist
pendingreqMode (pstamptool.c:320) : database error
-> p_psDBRunQuery (psDB.c:812): Database error generated by the server
Failed to execute SQL query. Error: Table 'gpc1.pstampRequest' doesn't exist
-> pendingreqMode (pstamptool.c:320): unknown psLib error
database error
This is a feature. (I plan on removing the postage stamp tables from the set created by pxadmin -create and adding a new mode to create them but I haven't gotten around to it yet).
Common Failures
Requests can fault for three reasons either at the parse stage or when finishing the request.
The most common fault gets set in the database as fault = 200. This happens when one of the source data stores responds with a HTTP 500 (Internal Server Error). MOPS' data store does this occasionally. These usually require no intervention as there is a revert task that will clear the fault allowing the system to try again.
Other request faults rarely happen and are usually due to software bug.
Jobs can fault due to typical nfs errors. There is a revert task for jobs. It only resets jobs with fault > 0 and < 10. Faults >= 10 are faults that are to be reported to the users. Jobs which are faulted in this way should have had their state set to stop thus they are finished.
The vast majority of the problems these days are related to the update processing. There are a large number of error conditions that can gum up the works. Here is an example
(
ipp032:~) bills% pst -pendingdependent -limit 1 pstampDependent MULTI pstampDependent METADATA dep_id S64 55261 state STR new stage STR chip stage_id S64 77563 component STR XY31 imagedb STR gpc1 outdir STR /data/ippdb02.0/pstamp/work/20100527/5977 rlabel STR ps_ud_WEB.UP need_magic BOOL T fault S16 0 priority S64 8 END
pstamp_checkdependent.pl sets chipRun 77563, class_id XY31 to update state and watches for it to go to 'full' state. Once it' goes to full it sets the magicDSRun to 'new' state. Once the component is destreaked chipProcessedImfile.magicked > 0 it's done and the pstampDependent is set to 'full'
The update processing is managed by the 'update' pantasks.
When a dependent run faults (that is when a update of a chipProcessedImfile, warpSkyfile, etc faults) the dependent is faulted as well. Thus to revert the dependent one needs to revert the underlying failure first and then revert the dependent. This is not yet done automatically.
For example say the dependent listed above fails due to an nfs error. The chipProcessedImfile.fault should be set to a PS_EXIT_SYS_ERROR (2). pstamp_checkdependent.pl will notice this and fault the dependent. It does this to avoid faulted dependents from filling up the pantasks queue thus preventing other dependents from running.
Later the dependent fault will be reverted and the dependency checking will run again. Hopefully the chip fault will have reverted and finished. After some number of dependency faults (3 currently) the server gives up and faults the job.
So if we have long periods of cluster trouble, postage stamp users will get lots of failed jobs.
How to clear these jobs?
- could just move offending request to hold state?
pstamptool -dbname ippRequestServer -dbserver $PSDBSERVER -updatereq -req_id 182918 -set_state hold
- change label priority until fixed/cleared? labeltool not working/right to use?
To make a request and it's jobs just go away set the request's state to goto_cleaned.
Postage Stamp Error Codes
typedef enum {
PSTAMP_SUCCESS = 0,
PSTAMP_FIRST_ERROR_CODE = 10,
PSTAMP_SYSTEM_ERROR = 10,
PSTAMP_NOT_IMPLEMENTED = 11,
PSTAMP_UNKNOWN_ERROR = 12,
PSTAMP_DUP_REQUEST = 20,
PSTAMP_INVALID_REQUEST = 21,
PSTAMP_UNKNOWN_PRODUCT = 22,
PSTAMP_NO_IMAGE_MATCH = 23,
PSTAMP_NOT_DESTREAKED = 24,
PSTAMP_NOT_AVAILABLE = 25,
PSTAMP_GONE = 26,
PSTAMP_NO_JOBS_QUEUED = 27,
PSTAMP_NO_OVERLAP = 28
} pstampJobErrors;
Monitoring the Apache Server
It is a good idea to check the proxy's Apache error log (/var/log/apace2/error_log) from time to time to look for unusual activity.
We get hourly requests from Google and Baidu for files long gone that their crawlers found prior to the time that we locked down the data store.
