How do I find a memory leak on my game server?

Profile the server's memory over uptime and correlate OOM crashes with uptime and session count: steadily climbing memory (and crashes after long uptime / many sessions) confirms per-session accumulation. Then cycle the server through many matches and players and watch what isn't released after sessions end, usually per-match state or per-player objects lingering due to retained references.

Why Does My Game Server Run Out of Memory?

Q: Why does my game server run out of memory?

Almost always a memory leak that accumulates over the server's long uptime, most commonly per-match or per-player data that isn't fully freed when matches end or players leave, so a little memory leaks each session and, over thousands of sessions, climbs until exhausted. A freshly-started server is fine; one up for hours/days under load runs out, the signature of per-session accumulation.

Q: How do I stop per-match memory from leaking on my server?

Audit the end-of-match and player-disconnect paths to ensure complete cleanup: when a match ends, release all its memory (state, spawned objects, buffers, and any references holding them alive); when a player leaves, release all their data and remove references to them. The common leak is per-session data almost-but-not-fully freed due to a lingering reference. Verify memory returns to baseline after each session rather than climbing over uptime.

Quick answer: Your game server runs out of memory almost always because of a memory leak that accumulates over the server's long uptime, most commonly per-match or per-player data that isn't fully freed when matches end or players leave, so memory creeps up with every session until exhausted. A freshly-started server is fine; one up for hours/days under load runs out, the signature of per-session accumulation.

Game servers run for a long time, hours or days, handling many matches and players in sequence, which makes them especially vulnerable to memory leaks: even a tiny leak per match adds up over thousands of matches until the server runs out of memory and crashes (dropping everyone).

Why Servers Run Out of Memory

Unlike a client (which restarts frequently), a server runs continuously, processing a stream of matches and players, so any memory not freed accumulates relentlessly. The classic cause: per-match or per-player data not cleaned up, when a match ends or a player disconnects, the memory associated with it (game state, player objects, buffers, event subscriptions) isn't fully released, so a little leaks each time, and over thousands of matches/players the memory climbs until exhausted.

The signature is server memory climbing steadily over uptime, and out-of-memory crashes correlated with how long the server has been running and how many sessions it's processed. Other causes (growing caches/logs over uptime) exist, but per-session accumulation is the most common.

How to Diagnose and Fix It

Profile the server's memory over uptime, does it climb steadily as it processes matches, or stay flat? Correlate out-of-memory crashes with uptime and session count. Bugnet captures crashes with context and version, so server OOM crashes, correlated with uptime/session count, confirm a leak pattern. Then cycle the server through many matches/players and watch what isn't released after sessions end.

Fix by ensuring complete cleanup of sessions and players: when a match ends, release all its memory (state, objects, buffers, and any references holding them alive); when a player leaves, release all their data and remove references to them. Verify memory returns to baseline after each session rather than climbing. See our guide on fixing a game server that runs out of memory.

Servers run for days, so a tiny per-match leak compounds into OOM. Ensure ended matches and departed players are fully freed, and verify memory returns to baseline each session.