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.\" $RCSfile: drmaa_session.3,v $     Last Update: $Date: 2008-07-08 09:10:04 $     Revision: $Revision: 1.9 $
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.\" Some handy macro definitions [from Tom Christensen's man(1) manual page].
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.TH drmaa_session 3 "$Date: 2008-07-08 09:10:04 $" "SGE 8.1.3pre" "Grid Engine DRMAA"
.\"
.\"
.\"
.SH NAME
drmaa_init, drmaa_exit \- Start/finish Grid Engine DRMAA session
.PP
.\"
.\"
.\"
.SH SYNOPSIS
.B #include """drmaa.h"""
.PP
.\"
.\"
.\"
.nf
\fBint drmaa_init(\fP
.RS
.BI "const char *" contact ,
.BI "char *" error_diagnosis ,
.BI size_t\  error_diag_len
.RE
.fi
\fB);\fP
.PP
.nf
\fBint drmaa_exit(\fP
.RS
.BI "char *" error_diagnosis ,
.BI size_t\  error_diag_len
.RE
.fi
\fB);\fP
.\"
.\"
.\"
.SH DESCRIPTION
.SS "drmaa_init()"
The drmaa_init() function initializes the Grid Engine DRMAA API library for all threads 
of the process and creates a new DRMAA session. This routine must be called once before 
any other DRMAA call, except for 
.M drmaa_version 3 ,
.M drmaa_get_DRM_system 3 ,
and 
.M drmaa_get_DRMAA_implementation 3 . 
Except for the above listed functions, no DRMAA functions may be called before
the drmaa_init() function \fIcompletes\fP.  Any DRMAA function which is called
before the drmaa_init() function completes will return a DRMAA_ERRNO_NO_ACTIVE_SESSION
error.
\fIContact\fP is an implementation dependent string which may be used to 
specify which Grid Engine cell to use. If 
\fIcontact\fP 
is NULL, the default Grid Engine cell will be used. In the 1.0 implementation 
\fIcontact\fP may have the following value: \fBsession=\fIsession_id\fP.  To
determine the session_id, the
.M drmaa_get_contact 3
function should be called after the session has already been initialized.  By
passing the \fBsession=\fIsession_id\fP string to the drmaa_init() function,
instead of creating a new session, DRMAA will attempt to reconnect to the
session indicated by the \fIsession_id\fP.  The result of reconnecting to a
previous session is that all jobs previously submitted in that session \fBthat
are still running\fP will be available in the DRMAA session.  Note, however,
that jobs which ended before the call to drmaa_init() may not be available or
may have no associated exit information or resource usage data.
.PP
.\" 
.SS "drmaa_exit()"
The drmaa_exit() function closes the DRMAA session for all threads and must be
called before process termination.  The drmaa_exit() function may be called only
once by a single thread in the process and may only be called after the
drmaa_init() function has completed.  Any DRMAA function, other than
.M drmaa_init 3 ,
which is called after the drmaa_exit() function completes
will return a DRMAA_ERRNO_NO_ACTIVE_SESSION error.
.PP
The drmaa_exit() function does necessary clean up of the DRMAA session state,
including unregistering from the
.M qmaster 8 .
If the drmaa_exit() function
is not called, the qmaster will store events for the DRMAA client until the
connection times out, causing extra work for the qmaster and consuming system
resources.
.PP
Submitted jobs are not affected by the drmaa_exit() function.
.PP
.\"
.\"
.SH "ENVIRONMENTAL VARIABLES"
.\"
.IP "\fBSGE_ROOT\fP" 1.5i
Specifies the location of the Grid Engine standard configuration files.
.\"
.IP "\fBSGE_CELL\fP" 1.5i
If set, specifies the default Grid Engine cell to be used. To address a Grid Engine
cell Grid Engine uses (in the order of precedence):
.sp 1
.RS
.RS
The name of the cell specified in the environment
variable SGE_CELL, if it is set.
.sp 1
The name of the default cell, i.e. \fBdefault\fP.
.sp 1
.RE
.RE
.\"
.IP "\fBSGE_DEBUG_LEVEL\fP" 1.5i
If set, specifies that debug information
should be written to stderr. In addition the level of
detail in which debug information is generated is defined.
.\"
.IP "\fBSGE_QMASTER_PORT\fP" 1.5i
If set, specifies the tcp port on which
the sge_qmaster is
expected to listen for communication requests.
Most installations will use a services map entry instead
to define that port.
.\"
.\"
.\"
.SH "RETURN VALUES"
Upon successful completion, drmaa_init() and drmaa_exit() return DRMAA_ERRNO_SUCCESS.
Other values indicate an error.
Up to \fIerror_diag_len\fP characters of error related diagnosis 
information is then provided in the buffer \fIerror_diagnosis\fP.
.PP
.\"
.\"
.\"
.SH "ERRORS"
The drmaa_init() and drmaa_exit() functions can fail with:
.\"
.TP
.B DRMAA_ERRNO_INTERNAL_ERROR
Unexpected or internal DRMAA error, like system call failure, etc.
.\" 
.TP
.B DRMAA_ERRNO_DRM_COMMUNICATION_FAILURE
Could not contact DRM system for this request.
.\" 
.TP
.B DRMAA_ERRNO_AUTH_FAILURE
The specified request is not processed successfully due to authorization failure.
.\" 
.TP
.B DRMAA_ERRNO_INVALID_ARGUMENT
The input value for an argument is invalid.
.\" 
.PP
The drmaa_init() function can fail with:
.TP
.B DRMAA_ERRNO_INVALID_CONTACT_STRING
Initialization failed due to invalid contact string.
.\" 
.TP
.B DRMAA_ERRNO_DEFAULT_CONTACT_STRING_ERROR
Could not use the default contact string to connect to DRM system.
.\" 
.TP
.B DRMAA_ERRNO_DRMS_INIT_FAILED
Initialization failed due to failure to init DRM system.
.\" 
.TP
.B DRMAA_ERRNO_ALREADY_ACTIVE_SESSION
Initialization failed due to existing DRMAA session.
.\" 
.TP
.B DRMAA_ERRNO_NO_MEMORY
Failed allocating memory.
.\" 
.PP
The drmaa_exit() function can fail with:
.TP
.B DRMAA_ERRNO_NO_ACTIVE_SESSION
Failed because there is no active session.
.\" 
.TP
.B DRMAA_ERRNO_DRMS_EXIT_ERROR
DRM system disengagement failed.
.PP
.\" 
.\" 
.\" 
.SH "SEE ALSO"
.M drmaa_submit 3 .