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Header |
/Engine/Source/Runtime/Core/Public/Misc/Fork.h |
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Include |
#include "Misc/Fork.h" |
class FForkProcessHelper
Helper functions for processes that fork in order to share memory pages.
About multithreading: When a process gets forked, any existing threads will not exist on the new forked process. To solve this we use forkable threads that are notified when the fork occurs and will automatically convert themselves into real runnable threads. On the master process, these forkable threads will be fake threads that are executed on the main thread and will block the critical path.
Currently the game code is responsible for calling Fork on itself than calling FForkProcessHelper::OnForkingOccured to transform the forkable threads. Ideally the fork point is done right after the game has loaded all the assets it wants to share so it can maximize the shared memory pool. From the fork point any memory page that gets written into by a forked process will be transferred into a unique page for this process.
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FRunnableThr... |
CreateForkableThread ( |
Creates a thread according to the environment it's in: In environments with SupportsMultithreading: create a real thread that will tick the runnable object itself In environments without multithreading: create a fake thread that is ticked by the main thread. |
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IsForkedChildProcess() |
Is this a process that was forked |
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IsForkedMultithreadInstance() |
Are we a forked process that supports multithreading This only becomes true after its safe to be multithread. |
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OnForkingOccured() |
Event triggered when a fork occurred on the child process and its safe to create real threads |
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SetIsForkedChildProcess() |
Sets the forked child process flag |
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SupportsMultithreadingPostFork() |
Tells if we allow multithreading on forked processes. |
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Name |
Description |
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bIsForkedChildProcess |
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bIsForkedMultithreadInstance |