Maximum execution time for Qiskit Runtime workloads

To ensure fairness and help control costs, there is a maximum amount of time each Qiskit Runtime job can run. If a job exceeds this time limit, it is forcibly canceled and a RuntimeJobMaxTimeoutError exception is raised.

Job maximum execution time

The maximum execution time for a job is the smaller of these values:

• The value set for max_execution_time
• The QPU-determined job timeout value

The max_execution_time value is based on quantum time, not wall clock time. Quantum time is the time spent by the QPU complex to process the job. Simulator jobs use wall clock time because they do not have quantum time.

Set the maximum execution time (in seconds) on the job options, as shown in the following example. See Specify options for information about setting options.

from qiskit_ibm_runtime import QiskitRuntimeService
from qiskit_ibm_runtime import EstimatorV2 as Estimator
 
service = QiskitRuntimeService()
backend = service.least_busy(operational=True, simulator=False)
 
estimator = Estimator(mode=backend)
 
estimator.options.max_execution_time = 2500

You can also find how much quantum time completed jobs have used by returning the job metrics as follows:

# Find quantum time used by the job
print(f"Quantum time used by job {job.job_id()} was {job.metrics()['usage']['quantum_seconds']} seconds")

QPU maximum execution time

The QPU calculates an appropriate job timeout value based on the input circuits and options. This QPU-calculated timeout is capped at 3 hours to ensure fair device usage. If a max_execution_time is also specified for the job, the lesser of the two values is used.

For example, if you specify max_execution_time=5000 (approximately 83 minutes), but the QPU determines it should not take more than 5 minutes (300 seconds) to execute the job, then the job is canceled after 5 minutes.

Session maximum execution time

When a session is started, it is assigned a maximum time to live (TTL) value. After this TTL is reached, the session is terminated, any jobs that are already running continue running, and any queued jobs that remain in the session are put into a failed state. For instructions to set the session maximum time, see Specify the session length.

Sessions also have an interactive time to live (ITTL) value between jobs that cannot be configured. If no session jobs are queued within that window, the session is temporarily deactivated.

To determine the maximum TTL and ITTL values for a session, use the session.details() method and look for the interactive_timeout and max_time values, respectively.

Batch maximum execution time

When a batch is started, it is assigned a maximum TTL value. After this TTL is reached, the batch is terminated, any jobs that are already running continue running, and any queued jobs that remain in the batch are put into a failed state. For instructions to set the batch maximum time, see Specify the batch length.

Batches also have an ITTL value between jobs that cannot be configured. If you don't explicitly close a batch, it is deactivated after the ITTL expires and can be reactivated at any time until it reaches its maximum TTL (usually 28800 seconds, or 8 hours).

To determine the ITTL and maximum TTL values for a batch, use the batch.details() method and look for the interactive_timeout and max_time values, respectively.

Other limitations

• Inputs to jobs cannot exceed 64MB in size.
• Open plan users can use up to 10 minutes of QPU execution time per month (resets at 00:00 UTC on the first of each month). QPU execution time is the amount of time that the QPU is dedicated to processing your job. You can track your monthly usage on the Platform dashboard, IBM Quantum™ Platform Workloads page, and Account page.

Next steps