{"id":7563,"date":"2026-08-14T23:30:04","date_gmt":"2026-08-14T21:30:04","guid":{"rendered":"https:\/\/ultimatemove.eu\/deadlocki-w-windows-jak-ich-unikac-i-co-z-nich-zrobic-aby-twoje-e-sportowe-sesje-byly-plynniejsze\/"},"modified":"2026-08-21T23:05:20","modified_gmt":"2026-08-21T21:05:20","slug":"deadlocks-in-windows","status":"publish","type":"post","link":"https:\/\/ultimatemove.eu\/en\/deadlocks-in-windows\/","title":{"rendered":"Deadlocks in Windows: how to spot them and how to avoid them"},"content":{"rendered":"
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The game freezes for two seconds in the middle of a duel. FPS reads 240 and the picture stands still. The server drops a tick even though the CPU is idling. Behind some of these cases sits a deadlock, a thread lock-up. This article shows how to recognise them and how to get rid of them.<\/p>\n\n\n\n

What a deadlock is<\/h2>\n\n\n\n

Deadlock from Valve… we write about it a lot - unfortunately this time we mean something less colourful - a system deadlock. It happens when two threads wait on each other for resources they have already locked. Thread A holds lock 1 and waits for lock 2. Thread B holds lock 2 and waits for lock 1. Neither gives way, so both stand still until the process dies.<\/p>\n\n\n\n

From the player perspective there is no load to see. The CPU has headroom, the GPU has headroom, and still nothing moves.<\/p>\n\n\n\n

Where it hurts in games and on servers<\/h2>\n\n\n\n
Area<\/th>Example in games<\/th>Consequences<\/th><\/tr><\/thead>
Client<\/strong><\/td>A lock on the render thread while a frame waits for network data<\/td>A stutter or a black screen at high FPS<\/td><\/tr>
Server<\/strong><\/td>Game logic waits for a result from another thread, for example from AI<\/td>Delays in state synchronisation, a drop in tick-rate<\/td><\/tr>
Matchmaking<\/strong><\/td>The player matching algorithm waits for data locked by another process<\/td>Longer queues, more timeouts when a map is assigned<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

How to detect deadlocks in Windows<\/h2>\n\n\n\n
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  1. Task Manager, Details tab.<\/strong> The Blocked<\/em> column shows processes stopped by a lock.<\/li>\n\n\n\n
  2. Process Explorer (Sysinternals).<\/strong> W Open Handles<\/code> look for the names of mutexes, files and COM objects held too long.<\/li>\n\n\n\n
  3. PerfMon.<\/strong> Counters MutexWait Time<\/code> and ThreadTimeInState(4)<\/code>, that is, time spent in the waiting state.<\/li>\n\n\n\n
  4. ETW and Debugging Tools.<\/strong> Enable the Microsoft-Windows-Debugger<\/em> provider and go through the stacks in WinDbg with the command ~* k<\/code>. Deadlocked threads sit on the same WaitForSingleObject<\/code> for the whole dump.<\/li>\n<\/ol>\n\n\n\n

    Where they come from<\/h2>\n\n\n\n