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sge_execd - the Execution Daemon

The execution daemon is responsible for the queue instances on its host and for the running of jobs in these queue instances. Periodically the execution daemon forwards to sge_qmaster information such as job status or load on its host.

Queues

A queue is a container for a class of jobs that are allowed to run on one or more hosts concurrently. A queue determines certain job attributes, for example, whether the job can be migrated. Throughout its lifetime, a running job is associated with its queue. Association with a queue affects some of the things that can happen to a job. For example, if a queue is suspended, all jobs associated with that queue are also suspended.

Jobs need not be submitted directly to a queue. You need to specify only the requirement profile of the job. A profile might include requirements such as memory, operating system, available software, and so forth. The grid engine software automatically dispatches the job to a suitable queue and a suitable host with a light execution load. If you submit a job to a specified queue, the job is bound to this queue. As a result, the grid engine system daemons are unable to select a lighter-loaded or better-suited device.

A queue can reside on a single host, or a queue can extend across multiple hosts. For this reason, grid engine system queues are also referred to as cluster queues. Cluster queues enable users and administrators to work with a cluster of execution hosts by means of a single queue configuration. Each host that is attached to a cluster queue receives its own queue instance from the cluster queue.

Client Commands

The command line user interface is a set of ancillary programs (commands) that enable you to do the following tasks:

  • Manage queues

  • Submit and delete jobs

  • Check job status

  • Suspend or enable queues and jobs

The grid engine system provides the following set of ancillary programs.

  • qacct - Extracts arbitrary accounting information from the cluster log file.

  • qalter - Changes the attributes of submitted but pending jobs.

  • qconf - Provides the user interface for cluster configuration and queue configuration.

  • qdel - Provides the means for a user, operator, or manager to send signals to jobs or to subsets thereof.

  • qhold - Holds back submitted jobs from execution.

  • qhost - Displays status information about execution hosts.

  • qlogin - Initiates a telnet or similar login session with automatic selection of a low-loaded, suitable host.

  • qmake - A replacement for the standard UNIX make facility. qmake extends make by its ability to distribute independent make steps across a cluster of suitable machines.

  • qmod - Enables the owner to suspend or enable a queue. All currently active processes that are associated with this queue are also signaled.

  • qmon - Provides an X Windows Motif command interface and monitoring facility.

  • qresub - Creates new jobs by copying running or pending jobs.

  • qrls - Releases jobs from holds that were previously assigned to them, for example, through qhold.

  • qrsh - Can be used for various purposes, such as the following.

    • To provide remote execution of interactive applications through the grid engine system. qrsh is comparable to the standard UNIX facility rsh.

    • To allow for the submission of batch jobs that, upon execution, support terminal I/O and terminal control. Terminal I/O includes standard output, standard error, and standard input.

    • To provide a submission client that remains active until the batch job finishes.

    • To allow for the grid engine software-controlled remote execution of the tasks of parallel jobs.

  • qselect - Prints a list of queue names corresponding to specified selection criteria. The output of qselect is usually fed into other grid engine system commands to apply actions on a selected set of queues.

  • qsh - Opens an interactive shell in an xterm on a lightly loaded host. Any kind of interactive jobs can be run in this shell.

  • qstat - Provides a status listing of all jobs and queues associated with the cluster.

  • qsub - The user interface for submitting batch jobs to the grid engine system.

  • qtcsh - A fully compatible replacement for the widely known and used UNIX C shell (csh) derivative, tcsh. qtcsh provides a command shell with the extension of transparently distributing execution of designated applications to suitable and lightly loaded hosts through grid engine software.

QMON, the Grid Engine System's Graphical User Interface

You can use QMON, the graphical user interface (GUI) tool, to accomplish most grid engine system tasks. Figure 1-3 shows the QMON Main Control window, which is often the starting point for both user and administrator functions. Each icon on the Main Control window is a GUI button that you click to start a variety of tasks. To see a button's name, which also describes its function, pass the pointer over the button.

Figure 1-3 QMON Main Control Window, Defined

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