Creating a HTCondor compute service

Table of Contents

• Overview
• Creating an HTCondor Service

Overview

HTCondor is a workload management framework that supervises task executions on various sets of resources. HTCondor is composed of six main service daemons (startd, starter, schedd, shadow, negotiator, and collector). In addition, each host on which one or more of these daemons is spawned must also run a master daemon, which controls the execution of all other daemons (including initialization and completion).

Creating an HTCondor Service

HTCondor is composed of a pool of resources in which jobs are submitted to perform their computation. In WRENCH, an HTCondor service represents a compute service (wrench::ComputeService), which is defined by the wrench::HTCondorComputeService class. An instantiation of an HTCondor service requires the following parameters:

• The name of a host on which to start the service;
• A std::set of 'child' wrench::ComputeService instances available to the HTCondor pool; and
• A std::map of properties (wrench::HTCondorComputeServiceProperty) and message payloads (wrench::HTCondorComputeServiceMessagePayload).

The set of compute services may include compute service instances that are either wrench::BareMetalComputeService or wrench::BatchComputeService instances. The example below creates an instance of an HTCondor service with a pool of resources containing a Bare-metal server:

// Simulation 
wrench::Simulation simulation;
simulation.init(&argc, argv);
 
// Create a bare-metal service
 
auto baremetal_service = simulation.add(
    new wrench::BareMetalComputeService(
          "execution_hostname",
          {std::make_pair(
                  "execution_hostname",
                  std::make_tuple(wrench::Simulation::getHostNumCores("execution_hostname"),
                                  wrench::Simulation::getHostMemoryCapacity("execution_hostname")))},
          "/scratch/"));
 
std::set<std::shared_ptr<wrench::ComputeService>> compute_services;
compute_services.insert(baremetal_service);
 
auto htcondor_compute_service = simulation->add(
          new wrench::HTCondorComputeService(hostname, 
                                      std::move(compute_services),
                                      {{wrench::HTCondorComputeServiceProperty::SUPPORTS_PILOT_JOBS, "false"}}
                                      ));

Jobs submitted to the wrench::HTCondorComputeService instance will be dispatched automatically to one of the 'child' compute services available to that instance (only one in the above example).