mirror of https://go.googlesource.com/go
34 lines
1.1 KiB
Go
34 lines
1.1 KiB
Go
// Copyright 2023 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build unix || wasip1
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package net
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import "syscall"
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// concurrentThreadsLimit returns the number of threads we permit to
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// run concurrently doing DNS lookups via cgo. A DNS lookup may use a
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// file descriptor so we limit this to less than the number of
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// permitted open files. On some systems, notably Darwin, if
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// getaddrinfo is unable to open a file descriptor it simply returns
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// EAI_NONAME rather than a useful error. Limiting the number of
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// concurrent getaddrinfo calls to less than the permitted number of
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// file descriptors makes that error less likely. We don't bother to
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// apply the same limit to DNS lookups run directly from Go, because
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// there we will return a meaningful "too many open files" error.
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func concurrentThreadsLimit() int {
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var rlim syscall.Rlimit
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if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlim); err != nil {
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return 500
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}
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r := rlim.Cur
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if r > 500 {
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r = 500
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} else if r > 30 {
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r -= 30
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}
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return int(r)
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}
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