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HQueue, or Houdini Queue, is a distributed job scheduling system. It consists of an HQueue server and a farm of processing nodes, or clients. The server accepts job submissions from users and assigns them to available clients.
The HQueue Simulation output driver submits dynamic simulation jobs to HQueue for distribution on the farm. The simulation is performed by the node specified in the Output Driver parameter. This is typically a 
Geometry ROP.
Parameters
Submit Job
Submits a simulation job to the HQueue system. If the submission is successful, then a dialog pops-up with the job’s id. The id can be used to track the simulation progress on HQueue’s web-based user interface.
General
Job Name
The name of the job. Set this to <default> or set blank if you want the default job name to be used.
Output Driver
The render node used to generate the output files. For most cases, this would be a path to a Geometry ROP.
HQueue Server
The machine name and listen port of the HQueue server.
Target HFS
The path to the Houdini distribution that will execute the simulation on the HQueue farm. The distribution must be installed in a location that is accessible by every machine on the farm. You can use the $HQROOT and $HQCLIENTARCH variables to help specify the folder path (see HQueue Variables).
Job Priority
The job’s priority. Jobs with higher priorities are scheduled and processed before jobs with lower priorities. 0 is the lowest priority.
Simulate Current HIP File
Choose this option if you want HQueue to simulate the .hip file that is currently open. The current .hip file must be in a location that is accessible by every machine on the farm. Note that any changes that are made to the .hip file while it is simulating on the farm are live. That is, any new changes may be applied to the simulation on the farm.
Simulate Target HIP File
Choose this option if you want HQueue to simulate another .hip file. The .hip file must be located somewhere that is accessible by every machine on the farm.
Copy Project Files to Shared Folder and Simulate
Choose this option if you want HQueue to simulate a copy of the currently opened .hip file. After clicking on the Render button, a file dependency dialog pops-up giving you an opportunity to choose the project files that are needed by the simulation. These files are copied to the destination specified by the Project Path parameter.
Target HIP
When Simulate Target HIP File is chosen, set this parameter’s value to the location of the .hip file to be loaded and simulated on the farm. The .hip file must be saved somewhere on the shared drive, or any other location that is accessible by every machine on the farm. You can use the $HQROOT variable to help specify the .hip file path (see HQueue Variables).
Project Path
When Copy Project Files to Shared Folder and Simulate is chosen, set this parameter’s value to the location on the shared folder where you want to copy your .hip file and its dependencies to. The location must be accessible by all machines on the farm. You can use the $HQROOT variable to help specify the .hip file path (see HQueue Variables).
Automatically Save HIP File
When checked, Houdini automatically saves the current .hip file before submitting a job to HQueue. This guarantees that the farm simulates with the latest changes made to your scene. This parameter does not apply when Simulate Target HIP File is chosen.
Warn If Unsaved Changes in HIP File
When checked, Houdini warns of any unsaved changes in the .hip file when submitting the job to HQueue. If this parameter is not checked, then Houdini ignores any unsaved changes and automatically submits the job to HQueue. This parameter does not apply when Render Target HIP File or Use Existing IFDs is chosen.
Report Submitted Job ID
When checked, Houdini shows a message stating the ID of the successfully submitted job. To avoid these messages, uncheck this parameter.
Partitioning Type
Choose how the simulation is to be partitioned and distributed on the farm.
Volume Slices
For volume simulations. The simulation is divided into slices using a 3-dimensional grid. Set the Slice Divisions parameter to set the properties of the grid.
The farm will set the variable SLICE to the slice number being simulated. This can be used for setting filesnames of the outputted geometry files.
Particle Slices
For particle simulations. The simulation is divided into slices using 1 or more slice planes. Set the Number of Slices parameter to indicate how many slices have been created by the planes.
The farm will set the variable SLICE to the slice number being simulated. This can be used for setting filesnames of the outputted geometry files.
Clusters
For simulations that have a Cluster node. The simulation is divided so that there is one job per cluster. Set the Cluster Node parameter to indicate which cluster should be used for the division.
The farm will set the variable CLUSTER to the cluster number being simulated. This can be used for setting filenames of the outputted geometry files.
Wedges
There is one job created per wedge for the wedge node specified by the Output Driver parameter.
The vairable WEDGE will be set to a string specifying the values changed for the wedge or the take used by the wedge. The variable WEDGENUM will be set to the wedge number being simulated.
Please see the 
Wedge ROP documentation for more information.
None
The simulation is not divided. Choose this option if you want to offload a simulation onto a single machine on the farm. This option is ideal for RBD, Cloth, and Wire simulations.
Slice Divisions
Describe how the simulation should be divided in the x, y and z-directions. Each slice created by the divisions requires a dedicated machine on the HQueue farm. For example, if the divisions are set to 2×2×2, then there would be 8 slices and the simulation would require a total of 8 machines.
Having more divisions allows for more work to be parallelized and generally improves simulation times. However, too many divisions can potentially slow down the simulation since more data must be passed between the slices.
Note that the number of slices dictates the number of generated geometry files. For instance, a simulation with 2 slices will create 2 sets of geometry files. So if 10 frames are to be simulated, then a total of 20 geometry files will be created, each file named with the slice number that it belongs to.
This parameter only applies if the Partitioning Type is set to Volume Slices.
Number of Slices
The total number of slices in the particle fluid simulation. HQueue will assign a client machine for each slice.
This parameter only applies if the Partitioning Type is set to Particle Slices.
Controls Node
The DOPs control node that assists HQueue in distributing the simulation. The node’s Tracker Address, Tracker Port and Slice Divisions parameters are automatically set by HQueue when the scene is processed on the farm.
This parameter does not apply if the Partitioning Type is set to None or Clusters.
Cluster Node
The Cluster node that specifies that clustering to be used to determine the distributed jobs.
This parameter only applies if the Partitioning Type is set to Clusters.
Email Options
Send Status Emails
Enable this parameter if you want status emails for the specified events to be sent out.
Note
The following parameters only apply when the Send Status Emails parameter is turned on.
Email Address
The list of emails that will be sent status updates. Use commas to separate the entries.
On Start
Enable this parameter to have emails sent when the job starts being processed by a client.
On Success
Enable this parameter to have emails sent when the job is successfully completed.
On Failure
Enable this parameter to have emails sent when the job has failed, been canceled, or abandoned.
On Pause
Enable this parameter to have emails sent when the job is paused.
On Resume
Enable this parameter to have emails sent when the job is resumed.
On Reschedule
Enable this parameter to have emails sent when a job is rescheduled.
On Priority Change
Enable this parameter to have emails sent when a job’s priority is changed.
Advanced
Assign To
Set this parameter if you want HQueue to assign the simulation job to a specific list of clients or client groups.
Any Client
When this option is selected, HQueue will assign your simulation jobs to any available machine.
Listed Clients
Choose this option to specify a list of client machines that HQueue can assign the simulation jobs to. When simulation volumes or particles, make sure that you list enough clients to meet the requirement set by the Slice Divisions or Number of Slices parameter.
Clients from Listed Groups
Choose this option to specify a list of client groups. HQueue will assign the simulation jobs to any machines that are members of at least one of the listed client groups.
Clients
The list of client machines that HQueue can assign the simulation jobs to. Use commas to separate the machine names.
This parameter only applies if Listed Clients is chosen in the Assign To parameter.
Select Clients
Click to pop-up a dialog with a list of client machines registered on the HQueue farm. Accepting the selection in the dialog automatically populates the Clients parameter with the selected clients.
Client Groups
The list of client groups that HQueue can assign the simulation jobs to. Use commas to separate the group names. Specifically, HQueue assigns simulation jobs to only the machines that are members of at least one of the groups in the list.
This parameter only applies if Clients from Listed Groups is chosen in the Assign To parameter.
Select Client Groups
Click to pop-up a dialog with a list of client groups registered on the HQueue farm. Accepting the selection in the dialog automatically populates the Client Groups parameter with the selected groups.
Use Dedicated Machine for Tracker
The tracker process coordinates the communication between the machines simulating the slices. It does very little work aside from receiving and sending messages to the other machines. By default, HQueue allows other simulation or render jobs to be assigned to the machine running the tracker.
Check this parameter to tell HQueue not to assign other jobs to the tracker machine. You may want to do this if you have several slices and you are worried that the communication from the client machines to the tracker will slow the tracker machine down.
This parameter does not apply when the Partitioning Type parameter is set to None or Clusters.
Enable Performance Monitor Logging
When checked, HQueue turns on performance monitor logging using the hscript perfmon command for the jobs doing the simulations. The log is merged with the job’s command output log and can be downloaded from the job view page on the HQueue web interface.
Set Number of CPUs per Job
Check this parameter if you want to set the maximum number of CPUs used for each simulation job.
CPUs per Job
The maximum number of CPUs that will be used by a simulation job. If the number exceeds a client machine’s number of CPUs, then the client machine will not be assigned to any simulation jobs.
Dependency Order
The rendering order to use when the target output driver has input ROP dependencies.
Frame by Frame
Renders a frame for all the output drivers in the network, and then moves on to the next frame. This method produces final results much faster than node by node, as the first final frame will be finished much sooner in the render process.
Node by Node
Renders the entire frame range for each output driver, before moving on to another one. This mode is more efficient overall, since some output driver types can execute faster in sequence than frame by frame. However, the first output frame is produced at almost the end of the render process.
Environment
A list of variable names and values that should be defined on the client machine when running the job. The variables appear as shell environment variables.
Create Directories
A list of output directories that should be created on the farm before any files are rendered out. For example, if your simulation generates a geometry files in $HIP/geo, then you will want to add this to the list.
Note
This parameter does nothing if the output directories already exist.
HQueue Variables
HQueue defines a set of variables which appear in the environment of a running job. You can use these variables to refer to common file paths, machine settings and server configuration values.
HQROOT
Evaluates to the root directory of the HQueue shared file system. The default HQueue installation sets this variable to /mnt/hq on Linux systems, H:/ on Windows systems, and /Volumes/HQShared on Mac OSX systems. Note that the shared file system can be configured to reside in a different location so check with your HQueue administrator for details.
HQCLIENTARCH
Evaluates to the architecture and operating system of the client machine assigned to execute the simulation job. For example, if the HQueue server assigned a job to a Linux, 64-bit machine on the farm, then $HQCLIENTARCH is set to 'linux-x86_64' in the environment.
This variable is useful for when you want to refer to paths that depend on the client machine’s platform. For example, /mnt/hq/houdini_distros/hfs.$HQCLIENTARCH could refer to the Houdini distribution to use for a simulation job. Specifically, it tells HQueue to use /mnt/hq/houdini_distros/hfs.linux-i686 when running the job on a 32-bit Linux machine, and to use /mnt/hq/houdini_distros/hfs.linux-x86_64 when running the job on a 64-bit Linux machine.
