Resource Limit Behavior for Memory-Intensive Processes

Direct answer

When a process in a Replit container exceeds its memory allocation, the Linux OOM killer terminates it with SIGKILL (signal 9). The process therefore exits with status 137 (128 + 9). The kernel logs the OOM event to the system log (visible via dmesg or journalctl), and Replit’s console typically shows a line like "Killed" or the exit code 137.

Replit does not expose a Nix‑based knob to tune the OOM‑killer’s behavior; the memory limit is set by the container’s cgroup configuration that Replit applies according to your account tier. You cannot configure a softer threshold inside the project’s Nix files.

Confirmed facts

• The OOM killer sends SIGKILL, not SIGSEGV or any other signal.
• Exit code 137 is the standard way a shell reports a process killed by signal 9.
• OOM events are recorded in the kernel ring buffer; they appear in dmesg output or journalctl -k with messages containing "out of memory" and the victim’s PID/command.
• Replit’s UI “Resources” tab reflects the cgroup memory limit; the actual limit can be inspected inside the container at /sys/fs/cgroup/memory.max (cgroup v2).

Likely explanation

Replit runs each repl in a isolated container that uses cgroups v2 to enforce the RAM quota. When the container’s memory usage hits memory.max, the kernel’s OOM selector chooses a task (usually the memory‑hungry process) and kills it with SIGKILL. Because the kill originates outside the process, the process does not get a chance to handle the event; it simply terminates and reports the signal‑derived exit code.

Steps to verify on your repl

1. Run a memory‑intensive test (e.g., a loop that allocates large buffers) and observe the console output.
2. After termination, check the exit code with echo $? – you should see 137.
3. Inspect the kernel log: dmesg | grep -i "out of memory" or journalctl -k | grep -i "out of memory" for a line mentioning your process.
4. Confirm the cgroup limit: cat /sys/fs/cgroup/memory.max – the value should match the RAM quota shown in the Replit Resources tab.

Missing diagnostic detail

If you observe an exit code different from 137, please share that value; it would indicate whether another signal (e.g., SIGSEGV) is involved and could change the recommendation.