repro_flush.py

"""Minimal repro for ray#60904: nsys report missing when GPU actor is profiled.
A/B on process_group_cleanup_enabled. Driver stays alive; actor exits explicitly.
"""
import argparse, glob, os, subprocess, sys, time
import ray

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--group-cleanup", choices=("on", "off"), default="on")
    ap.add_argument("--teardown", choices=("wait", "immediate"), default="wait")
    args = ap.parse_args()
    cfg = {} if args.group_cleanup == "on" else {"process_group_cleanup_enabled": False}
    ctx = ray.init(address="local", num_gpus=1, include_dashboard=False,
                   _system_config=cfg, logging_level="ERROR")
    session = ctx.address_info["session_dir"]

    nsight = {"t": "cuda,nvtx", "sample": "none", "cpuctxsw": "none",
              "stop-on-exit": "true"}

    @ray.remote(num_gpus=1, runtime_env={"nsight": nsight}, max_restarts=0)
    class GpuActor:
        def work(self):
            import torch
            x = torch.randn(2048, 2048, device="cuda")
            for _ in range(30):
                x = x @ x
            torch.cuda.synchronize()
            return os.getpid()
        def stop(self):
            ray.actor.exit_actor()

    a = GpuActor.remote()
    wpid = ray.get(a.work.remote())
    # process tree snapshot while alive
    tree = subprocess.run(["ps", "-o", "pid,ppid,pgid,stat,args", "-p", str(wpid)],
                          capture_output=True, text=True).stdout
    print(f"[{args.group_cleanup}] worker python PID={wpid}")
    print(tree.strip())
    if args.teardown == "immediate":
        # Mirror workload's ds.materialize() -> ray.shutdown() with no wait.
        del a
        ray.shutdown()
        reps = glob.glob(f"{session}/logs/nsight/*.nsys-rep")
        ok = reps and os.path.getsize(reps[0]) > 0
        print(f"[{args.group_cleanup}/immediate] RESULT: {'REP OK' if ok else 'NO REP'}")
        return
    try:
        ray.get(a.stop.remote())
    except Exception:
        pass
    # driver stays alive; poll for the rep for up to 20s
    reps = []
    for _ in range(20):
        time.sleep(1)
        reps = glob.glob(f"{session}/logs/nsight/*.nsys-rep")
        if reps and os.path.getsize(reps[0]) > 0:
            break
    if reps and os.path.getsize(reps[0]) > 0:
        print(f"[{args.group_cleanup}] RESULT: REP OK ({os.path.getsize(reps[0])//1024} KB)")
    else:
        print(f"[{args.group_cleanup}] RESULT: NO REP (nsight dir: {glob.glob(session+'/logs/nsight/*')})")
    ray.shutdown()

if __name__ == "__main__":
    main()