drms_server
Synopsis: drms_server [-f] [-L] [-h] [-v] [-s] [-n]
Usage: drms_server [-h]
drms_server [-Vsnf]
Options: -h: Print this help message.
-V: Verbose debug output.
-A: Archive SUs opened for writing during this session.
-L: Redirect stdout and stderr to SU log files.
-f: Run server in the foreground.
-s: Commit after every module exit and continue after
errors.
-n: Turn off Nagle's algorithm on TCP/IP sockets.
Additional parameters:
params for database connection, if these are NULL drms_server gets the values from ~/.pgpass
JSOC_DBHOST(NULL)
JSOC_DBNAME(NULL)
JSOC_DBUSER(NULL)
JSOC_DBPASSWD(NULL)
params for default overrides
DRMS_RETENTION(-1) Retention in days. If not -1 then this value overrides
the retention time for storage units created by this
session. Server only.
DRMS_QUERY_MEM(512) Maximum amount of memory (in MB) used by a single record query.
Note this is for the record information, not segment size.
DRMS_SERVER_WAIT(1) Non-zero value indicates waiting 2 seconds before exiting, otherwise don't wait.
From environment:
USERdrms_server starts the DRMS server program for a user's session. Each session has its own instance of the drms_server program running. drms_server is usually run from withing the drms_run (see DrmsRunCmd) script but can also be run in a script created by a user when multiple pipeline modules will be run inside a single session.
The "-f" flag makes the server run in the foreground. Without "-f" the drms_server command spawn a server in a background process, prints the connection info to stdout and exits.
The "-L" flag turns off saving the server stdout and stderr in SUMS and cataloged in the session table.
The following notes may need to be updated:
Running one or more DRMS modules involves three main steps
a) starting a DRMS session,
b) runnning the module(s) and
c) closing the session.
The final step will either commit all the data generated by
modules in the session or discard it if an error occured.
The script /jsoc/scripts/drms/drms_run automates the three steps
detailed below, and allows modules (or scripts containing multiple
module commands) to be run with a single command.
The command
host:~> drms_run <command> [options...]
will start a new DRMS server, run <command> and depending on the exit
status of <command> will either commit or discard changes to the
database and stop the DRMS server. drms_run will use the drms_server
executable pointed to by the environment variable DRMS_SERVER_EXE. If
DRMS_SERVER_EXE is not set drms_run will assume that an executable
"drms_server" is in your path. The output from the DRMS server is
piped to the file pointed to by the environment variable
DRMS_LOGFILE. If DRMS_SERVER_EXE is not set drms_run will create a log
file in /tmp/DRMS.<pid>, where pid is the PID of the drms_run
script interpreter.
The three steps are carried out as follows:
a) Before you run modules you must have a DRMS server running to
act as a session master. This can be done by running the command
host:~> jsoc/bin/<target>/drms_server -f
The server will print out what interface it is listening
for connections on. For example:
akhenaten:~/jsoc> bin/custom.akhenaten/drms_server -f
DRMS_HOST = akhenaten.Stanford.EDU
DRMS_PORT = 33137
DRMS_PID = 20955
DRMS_SESSIONID = 946
DRMS_SUNUM = 28201
DRMS_SUDIR = /SUM5/D28201
DRMS server started with pid=20955, noshare=0, noroe=0
...
The "-f" flag makes the server run in the foreground. Without
"-f" the drms_server command spawn a server in a background
process, prints the connection info to stdout (as above)
and exits.
The server will print log messages to stdout and
stderr. These will be copied (tee'ed) into files named drms_server.stdout and drms_server.stderr
in the DRMS_SUDIR directory unless the "-L" nolog flag is given to drms_server.
should be piped to a file if you intend to keep them. DRMS_SUDIR is provided by SUMS
with the SUMS index DRMS_SUNUM. The SUMS directory is kept in the drms_session table for
the current namespace in which drms_server is run during the session or when drms_server aborts.
If drms_server commits, the SUMS directory is set to NULL in the drms_session table.
The retention time is set to the max of retention times of records saved in the same session
unless overridden with the "DRMS_RETENTION" parameter to drms_server.
The logs are kept in DRMS_LOG_TAPEGROUP.
b) Now you can run the module(s). The modules do not need to run on
the same host as the server. They can run on any host as long as
they are able to open a TCP socket connection to the server
process.
When running a module, the named parameter DRMSSESSION must be set
to indicate the host and port where the DRMS server is listening
for connection attempts. It is perhaps most convenient to do this
by setting the environment variable DRMSSESSION. In the example above
this would mean executing the command:
akhenaten:~/jsoc> setenv DRMSSESSION akhenaten:33137
Each module that connects causes the server to spawn a new thread
to service the new client. The server can service multiple
clients simultaneously, but database operations are serialized
within the server and executed sequentially using a shared
connection to the DRMS database.
3. When all modules have finished successfully you can either
a) tell the DRMS server stop and commit all data generated or
modified by the modules to the DRMS database by sending a
SIGUSR1 signal to it. In the example above that would mean
issuing the command
akhenaten:~/jsoc> kill -s USR1 20955
or if an error occurs you can
b) tell the DRMS server to abort and discard all data generated
by the modules by sending it a SIGTERM, SIGQUIT or SIGINT.
In the example above that could be done by pressing CTRL-C
in the terminal where the server is running or by issuing
the command
akhenaten:~/jsoc> kill -s INT 20955
It should be safe to kill the server with SIGKILL (kill -9).
It will have the same effect as a regular abort except that it
leaves a stale entry in DRMS's active session table.