Resource Requirements Reference

Technical reference for job resource specifications and allocation strategies.

Resource Requirements Fields

Field	Type	Required	Default	Description
`name`	string	Yes	—	Identifier to reference from jobs
`num_cpus`	integer	No	`1`	Number of CPU cores
`num_gpus`	integer	No	`0`	Number of GPUs
`num_nodes`	integer	No	`1`	Number of nodes per job (`srun --nodes`); allocation size is set via Slurm scheduler config
`memory`	string	No	`1m`	Memory allocation (see format below)
`runtime`	string	No	`PT1H`	Maximum runtime (ISO 8601 duration)

Example

resource_requirements:
  - name: small
    num_cpus: 2
    num_gpus: 0
    num_nodes: 1
    memory: 4g
    runtime: PT30M

  - name: large
    num_cpus: 16
    num_gpus: 2
    num_nodes: 1
    memory: 128g
    runtime: PT8H

  - name: mpi_job       # multi-node MPI or Julia Distributed.jl
    num_cpus: 32
    num_nodes: 4        # each job step spans 4 nodes
    memory: 128g
    runtime: PT8H

`num_nodes`

The num_nodes field controls how many nodes each job step spans (srun --nodes). The Slurm allocation size (sbatch --nodes) is set separately via the Slurm scheduler configuration.

For most jobs the value is 1 (default). Set it to a larger value for multi-node jobs such as MPI or Julia Distributed.jl. For single-node jobs in a multi-node allocation, keep num_nodes=1 and configure the allocation size on the Slurm scheduler.

See Multi-Node Jobs for detailed examples and guidance.

Memory Format

String format with unit suffix:

Suffix	Unit	Example
`k`	Kilobytes	`512k`
`m`	Megabytes	`512m`
`g`	Gigabytes	`16g`

Examples:

memory: 512m    # 512 MB
memory: 1g      # 1 GB
memory: 16g     # 16 GB

Runtime Format

ISO 8601 duration format:

Format	Description	Example
`PTnM`	Minutes	`PT30M` (30 minutes)
`PTnH`	Hours	`PT2H` (2 hours)
`PnD`	Days	`P1D` (1 day)
`PnDTnH`	Days and hours	`P1DT12H` (1.5 days)

Examples:

runtime: PT10M      # 10 minutes
runtime: PT4H       # 4 hours
runtime: P1D        # 1 day
runtime: P1DT12H    # 1 day, 12 hours

Job Allocation Strategies

Resource-Based Allocation (Default)

The server considers each job's resource requirements and only returns jobs that fit within available compute node resources.

Behavior:

Considers CPU, memory, and GPU requirements
Prevents resource over-subscription
Enables efficient packing of heterogeneous workloads

Configuration: Run without --max-parallel-jobs:

torc run $WORKFLOW_ID

Queue-Based Allocation

The server returns the next N ready jobs regardless of resource requirements.

Behavior:

Ignores job resource requirements
Only limits concurrent job count
Simpler and faster (no resource calculation)

Configuration: Run with --max-parallel-jobs:

torc run $WORKFLOW_ID --max-parallel-jobs 10

Use cases:

Homogeneous workloads where all jobs need similar resources
Simple task queues
When resource tracking overhead is not wanted

Resource Tracking

When using resource-based allocation, the job runner tracks:

Resource	Description
CPUs	Number of CPU cores in use
Memory	Total memory allocated to running jobs
GPUs	Number of GPUs in use
Nodes	Number of jobs running per node

Jobs are only started when sufficient resources are available.

Keyboard shortcuts

Torc Documentation