remove sleep infinity idle_timeout - prevents modal idle_timeout

Author: manascb1344

runner/config.py

@@ -94,16 +94,6 @@
 # Backoff delays in seconds for sandbox spawn retries (exponential)
 SANDBOX_RETRY_BACKOFF = [1, 2, 4]
 
-# Sandbox idle timeout — keeps sandbox warm after runner exits, avoids full cold start
-# for subsequent jobs. The sandbox entrypoint stays alive (dockerd + keepalive) after
-# the runner completes. If no new job claims it within this window, Modal auto-terminates.
-# Default: 5 minutes. Set to 0 to disable.
-try:
-    IDLE_TIMEOUT_SECONDS = max(0, int(os.environ.get("IDLE_TIMEOUT_SECONDS", "300")))
-except ValueError:
-    logging.getLogger("runner").warning("Invalid IDLE_TIMEOUT_SECONDS; using default=300")
-    IDLE_TIMEOUT_SECONDS = 300
-
 
 def get_gpu_config(gpu_key: str):
     """Resolve a GPU label key to a Modal GPU config object."""

runner/services/sandbox_service.py

@@ -7,7 +7,6 @@
     ALLOWED_CIDRS,
     BLOCK_NETWORK,
     CACHE_VOLUME_NAME,
-    IDLE_TIMEOUT_SECONDS,
     MODAL_REGION,
     RUNNER_VERSION,
     SANDBOX_EXTRA_ENV,
@@ -109,12 +108,10 @@ def build_runner_image() -> modal.Image:
 # Pre-built image instance for reuse
 runner_image = build_runner_image()
 
-# Sandbox entrypoint — unified dockerd + runner in a single command chain.
-# dockerd starts in background. The dockerd wait + image load are also backgrounded,
-# so the runner starts IMMEDIATELY without waiting for dockerd.
+# Sandbox entrypoint — starts dockerd in background and immediately launches the runner.
+# The dockerd wait + image load run in the background so the runner starts without delay.
 # Non-Docker jobs skip the 60s dockerd startup entirely.
-# After the runner exits, sleep infinity keeps the sandbox alive.
-# idle_timeout terminates the sandbox after a period of inactivity.
+# After the runner exits, the entrypoint ends and the sandbox terminates normally.
 SANDBOX_CMD = (
     "bash -c '/start-dockerd.sh &'"
     " && (for i in $(seq 1 60); do docker info > /dev/null 2>&1 && break; sleep 1; done;"
@@ -123,7 +120,6 @@ def build_runner_image() -> modal.Image:
     " && export RUNNER_ALLOW_RUNASROOT=1"
     " && export DOCKER_BUILDKIT=1"
     " && ./run.sh --jitconfig \"$GHA_JIT_CONFIG\" 2>&1 | tee /tmp/runner.log"
-    " && sleep infinity"
 )
 
 
@@ -151,8 +147,6 @@ async def spawn_sandbox(
         volumes=sandbox_volumes,
         experimental_options={"enable_docker": True},
     )
-    if IDLE_TIMEOUT_SECONDS > 0:
-        sandbox_kwargs["idle_timeout"] = IDLE_TIMEOUT_SECONDS
     if MODAL_REGION:
         sandbox_kwargs["region"] = MODAL_REGION