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Asp .net core memory management mechanism

Note: when garbage collection is triggered, all threads except the thread that triggers the garbage collection will suspend state

Classification:

Mainly divided into server GC and workstation GC

Server GC:

Default value

For multicore systems, it creates a GC Heap for each processor and performs post-session operations concurrently (concurrent was the default before. Net framework4.5, but later replaced with backgroud).

Features: the initial allocation of memory is large (each cpu has to be allocated, it takes up a lot of memory). At the same time, this mode believes that memory is used, and there is waste if it is not occupied. At the same time, frequent GC will cause a waste of system resources, so it is basically how much memory it takes.

Usage scenarios: applications that have few applications and eat memory on the server

Workstation GC:

Workstation GC occurs on the user thread, which usually runs at a normal priority, so in this mode the garbage collector must compete with other threads for CPU time. Of course, it will not suspend the thread running native code, but it will cause other threads to hang live.

It can be in concurrent mode, or it can be disabled.

Usage scenario: there are many applications on the server, and concurrent garbage collection needs to be disabled. Reason: reduce cpu context switching and improve machine performance.

Here's a mention of background workstation GC.

Background workstation GC: collection of generation 0 and generation 1 during background work garbage collection is called foreground garbage collection. When foreground garbage collection occurs, all managed threads will be suspended.

When background garbage collection is in progress and you have allocated enough objects in generation 0, CLR will perform generation 0 or generation 1 foreground garbage collection.

A dedicated background garbage collection thread checks at common security points to determine if there is a request for foreground garbage collection.

If it exists, the background collection will suspend itself so that the foreground garbage collection can occur. After the foreground garbage collection is complete, dedicated background garbage collection threads and user threads will continue.

Background server GC background service garbage collection: this is the default mode, similar to the background workstation GC function. Different from workstation GC background work garbage collection: one is multithreaded, and the other is a dedicated background garbage collection thread.

Application

Docker scene

Please use workstation GC mode, that is, set server GC to false.

If you use server GC, you may have the problem that the container restarts frequently (up to the maximum memory allocation).

Reference documentation:

Https://blog.markvincze.com/troubleshooting-high-memory-usage-with-asp-net-core-on-kubernetes/

Https://docs.microsoft.com/en-us/dotnet/standard/garbage-collection/fundamentals

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