Session Configuration

There are several configurations options for the application.

The configurations can be set by:

app = Rocketry(config={
    'task_execution': 'process',
    'task_pre_exist': 'raise',
    'force_status_from_logs': True,

    'silence_task_prerun': False,
    'silence_task_logging': False,
    'silence_cond_check': False,

    'max_process_count': 5,
    'restarting': 'replace',
    'cycle_sleep': 0.1

This can be later accessed via:

>>> app.session.config.task_execution


Session config is a Pydantic instance. You can also modify this on runtime.


task_execution: How tasks are run by default.


  • main: no parallelization

  • async: run async if can (default in the future)

  • thread: on separate thread

  • process: on separate process (default)

task_pre_exist: What happens if a task with given name already exists.


  • raise: An error is thrown (default)

  • rename: the task is renamed (numbers added after the name)

  • ignore: The task is simply not inserted to the session

force_status_from_logs: Use logs always to determine the task statuses or times.

If set as:

  • True: Logs are always read when checking the statuses. Robust but less performant.

  • False: If cached status found, it is used instead. (default)

silence_task_prerun: Whether to silence errors occurred during starting up a task.

If set as:

  • True: The scheduler does not crash on errors occurred on the startup of a task.

  • False: The scheduler crashes. Useful for debug but not for production. (default)

A failure in prerun commonly occurs when there are arguments that cannot be pickled or materialized. If task fails in prerun, it cannot simply be run.

silence_task_logging: Whether to silence errors occurred during logging a task.

If set as:

  • True: The scheduler does not crash on errors occurred when logging a task.

  • False: The scheduler crashes. Useful for debug but not for production. (default)

A failure in task logging commonly occurs if there are connection problems with the logging repository. Failure in logging might be severe as it leads to that Rocketry is unable to maintain the history of what tasks ran and when causing some conditions to be inaccurate.

silence_cond_check: Whether to silence errors occurred when checking conditions’ values.

If set as:

  • True: The scheduler does not crash on errors occurred on checking conditions

  • False: The scheduler crashes. Useful for debug but not for production. (default)

multilaunch: Whether to allow parallel runs of the same task.

In other words, whether to allow a task that is already running to start again. By default, False. Session-level option not used if specified to a task.

max_process_count: Maximum number of processes allowed to be started.

By default, the number of CPUs.

restarting: How the scheduler is restarted (if restart is called).


  • replace: Restart by replacing the current process (default)

  • relaunch: Restart by starting a new process

  • fresh: Restart by starting a new process (on new window on Windows)

  • recall: Restart by calling the start method again. Useful for testing the restart

cycle_sleep: How long is waited (in seconds) after the scheduler goes through one round of tasks.

If None, no sleep and the scheduler is as agressive as it can. If it is too low the system might take a lot of CPU and if too high, the scheduler might not be accurate.

By default it is set to 0.1.

instant_shutdown: Whether to terminate all tasks on shutdown.

If set False, the scheduler will wait till all tasks finish on shutdown. Running tasks that are past their timeout or their end_cond are true, are terminated normally. If set True, the scheduler will always terminate all running tasks on shutdown. Shutdown will still wait till all threads are finished.

By default, False.

param_materialize: When to turn arguments to actual values.

Whether to turn the arguments to actual values before or after creating threads (for execution="thread) and processes (for execution="process). Options:

  • pre: Before thread/process creation.

  • post: After thread/process creation. (default)

Only applicable for some argument types and materialization type specified in the argument itself overrides configuration setting.

timezone: Timezone for scheduling.

Timezone to be used in evaluating time related condition and displaying datetime. Should be datetime.timezone. One alternative is to use pytz.

By default, use system default.

time_func: Function for time measurement.

Function that returns current time in seconds since epoch similar to time.time(). Used throughout Rocketry including in condition evaluation and logging. Useful only for testing purposes.

By default, use time.time.

cls_lock: Lock class for tasks.

Lock class used for preventing modifying tasks or checking their status elsewhere at the same time. You may override this with a custom lock if you need to run multiple instances of the same application at the same time. The class should have context manager and methods acquire, release and locked. By default, threading.Lock.