feat(server): Better connection memory tracking #2205
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src/server/CMakeLists.txt
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| @@ -28,7 +28,7 @@ if (NOT APPLE) | |||
| endif() | |||
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| add_library(dragonfly_lib engine_shard_set.cc channel_store.cc command_registry.cc | |||
| config_registry.cc conn_context.cc debugcmd.cc dflycmd.cc | |||
| config_registry.cc conn_context.cc debugcmd.cc dflycmd.cc allocation_sampler.cc | |||
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maybe we can split this PR to few PRs?
for example I believe AllocationSampler can be in a seprate PR
| @@ -98,8 +100,8 @@ class RedisParser { | |||
| absl::InlinedVector<std::pair<uint32_t, RespVec*>, 4> parse_stack_; | |||
| std::vector<std::unique_ptr<RespVec>> stash_; | |||
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| using BlobPtr = std::unique_ptr<uint8_t[]>; | |||
| std::vector<BlobPtr> buf_stash_; | |||
| using Blob = std::vector<uint8_t>; | |||
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can you extract this change as well to a new PR?
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it is part of this PR though, because that's the only way we can do tracking (we have no way of getting the array size)
| // We add a hardcoded 9k value to accomodate for the part of the Fiber stack that is in use. | ||
| // The allocated stack is actually larger (~130k), but only a small fraction of that (9k | ||
| // according to our checks) is actually part of the RSS. | ||
| mem += 9'000; |
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Don't we account for the dispatch fiber here as well?
So shouldn't it be:
mem += 9k; // unconditional main fiber
if (dispatch_fb_.IsJoinable())
mem += 9k
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That's a nice observation.
An actual test of creating many connections show an average of 9kb per connection.
All of these connections send a PING, and then later randomly (and slowly) created string keys.
I imagine that PING creates a dispatch fiber, and as such, it should already be included in the 9kb. In other words, maybe it should be
constexpr size_t kMinimalFiberStackKb = 4'500;
mem += kMinimalFiberStackKb;
if (dispatch_db_.IsJoinable())
mem += kMinimalFiberStackKb;However, I would like to check this with and without issuing a PING to make sure it works as expected. Stay tuned :)
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To clarify, I also created a simple test to make sure that using a Fiber's stack actually increases RSS (in addition to creating that stack). But the 9k part comes from experimenting with the actual connection fibers (as it depends how much of the stack is used)
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