Parent flow crashes immediately after all subflows are completed

Help
,
1

I’m encountering an issue where the parent flow crashes immediately after the subflow is completed. I am using run_deployment to execute the subflow, and while the subflow finishes successfully, the parent flow transitions to a crashed state right after the subflow completion.

The following error is logged:

Process for flow run 'aspiring-cockatoo' exited with status code: -9; This indicates that the process exited due to a SIGKILL signal. Typically, this is either caused by manual cancellation or high memory usage causing the operating system to terminate the process.
11:28:18 AM
prefect.flow_runs.runner
Reported flow run '54e4deb7-a72d-42e5-877e-e82f6941ffbc' as crashed: Flow run process exited with non-zero status code -9.

Some additional context:

  • The subflow does not return any result data.
  • Resources are sufficient: CPU (16 cores), Memory (32 Gi). Based on top output, memory usage appears to be well within limits just before the parent flow crashes.
  • Here is the top output from the parent flow container right before the crash:
PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                 
      1 root      20   0 4361048 354936  89356 S  91.7  0.5   0:06.13 prefect                                 
    178 root      20   0       0      0      0 Z   0.0  0.0   0:03.76 python                                  
    303 root      20   0   18524   3436   3004 S   0.0  0.0   0:00.00 bash                                    
    313 root      20   0   36660   3180   2700 R   0.0  0.0   0:00.09 top

Below is the code I’m using to deploy the subflow within the parent flow. After logging the flow run state, the parent flow also terminates:

from prefect.deployments import run_deployment
flow_run = run_deployment(
            name=name,
            flow_run_name=flow_run_name,
            parameters=parameter_dict,
            timeout=0,
        )
logger.info(f"State for flow_run: {flow_run.state}")

Given that there doesn’t appear to be any memory issues based on top output and the subflow completes successfully without returning any result, I’m unsure why the parent flow is crashing. Any insights would be appreciated.