http server IO wait too long

[bchain618]

when we print go routine stack trace using pprof, we found a routine with (net.(*conn).Read) have last 1129 minutes, this is the stack trace:

goroutine 29761 [IO wait, 1129 minutes]: internal/poll.runtime_pollWait(0x7f5cac327420, 0x72, 0xc0050cda58) /usr/lib/golang/src/runtime/netpoll.go:173 +0x66 internal/poll.(*pollDesc).wait(0xc006000a18, 0x72, 0xffffffffffffff00, 0x104e6c0, 0x197d8a8) /usr/lib/golang/src/internal/poll/fd_poll_runtime.go:85 +0x9a internal/poll.(*pollDesc).waitRead(0xc006000a18, 0xc000a13000, 0x1000, 0x1000) /usr/lib/golang/src/internal/poll/fd_poll_runtime.go:90 +0x3d internal/poll.(*FD).Read(0xc006000a00, 0xc000a13000, 0x1000, 0x1000, 0x0, 0x0, 0x0) /usr/lib/golang/src/internal/poll/fd_unix.go:169 +0x179 net.(*netFD).Read(0xc006000a00, 0xc000a13000, 0x1000, 0x1000, 0xc0050cdb88, 0xc0050cdb68, 0x6f324a) /usr/lib/golang/src/net/fd_unix.go:202 +0x4f net.(*conn).Read(0xc0000a71c0, 0xc000a13000, 0x1000, 0x1000, 0x0, 0x0, 0x0) /usr/lib/golang/src/net/net.go:177 +0x68 net/http.(*connReader).Read(0xc006881500, 0xc000a13000, 0x1000, 0x1000, 0x0, 0x0, 0x0) /usr/lib/golang/src/net/http/server.go:786 +0xfc bufio.(*Reader).fill(0xc00623b5c0) /usr/lib/golang/src/bufio/bufio.go:100 +0x10f bufio.(*Reader).Peek(0xc00623b5c0, 0x4, 0x0, 0x0, 0x0, 0x0, 0x51625b) /usr/lib/golang/src/bufio/bufio.go:132 +0x3f net/http.(*conn).readRequest(0xc008f261e0, 0x1055d20, 0xc006170280, 0x0, 0x0, 0x0) /usr/lib/golang/src/net/http/server.go:963 +0xb27 net/http.(*conn).serve(0xc008f261e0, 0x1055d20, 0xc006170280) /usr/lib/golang/src/net/http/server.go:1788 +0x49e created by net/http.(*Server).Serve /usr/lib/golang/src/net/http/server.go:2851 +0x2f5