Datasets:

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sharjeelyunus

/

github-issues-dataset

like 5

ERROR: type should be string, got "https://golang.org/cl/84897 introduces a denial-of-service attack on `json.Marshal` via a live-lock situation with `sync.Pool`.\r\n\r\nConsider [this snippet](https://play.golang.org/p/htet7ILi9oJ):\r\n```go\r\ntype CustomMarshaler int\r\n\r\nfunc (c CustomMarshaler) MarshalJSON() ([]byte, error) {\r\n\ttime.Sleep(500 * time.Millisecond) // simulate processing time\r\n\tb := make([]byte, int(c))\r\n\tb[0] = '\"'\r\n\tfor i := 1; i < len(b)-1; i++ {\r\n\t\tb[i] = 'a'\r\n\t}\r\n\tb[len(b)-1] = '\"'\r\n\treturn b, nil\r\n}\r\n\r\nfunc main() {\r\n\tprocessRequest := func(size int) {\r\n\t\tjson.Marshal(CustomMarshaler(size))\r\n\t\ttime.Sleep(1 * time.Millisecond) // simulate idle time\r\n\t}\r\n\r\n\t// Simulate a steady stream of infrequent large requests.\r\n\tgo func() {\r\n\t\tfor {\r\n\t\t\tprocessRequest(1 << 28) // 256MiB\r\n\t\t}\r\n\t}()\r\n\r\n\t// Simulate a storm of small requests.\r\n\tfor i := 0; i < 1000; i++ {\r\n\t\tgo func() {\r\n\t\t\tfor {\r\n\t\t\t\tprocessRequest(1 << 10) // 1KiB\r\n\t\t\t}\r\n\t\t}()\r\n\t}\r\n\r\n\t// Continually run a GC and track the allocated bytes.\r\n\tvar stats runtime.MemStats\r\n\tfor i := 0; ; i++ {\r\n\t\truntime.ReadMemStats(&stats)\r\n\t\tfmt.Printf(\"Cycle %d: %dB\\n\", i, stats.Alloc)\r\n\t\ttime.Sleep(time.Second)\r\n\t\truntime.GC()\r\n\t}\r\n}\r\n```\r\n\r\nThis is a variation of https://github.com/golang/go/issues/23199#issuecomment-353193866 of a situation suggested by @bcmills.\r\n\r\nEssentially, we have a 1-to-1000 ratio of a routines that either use 1KiB or 256MiB, respectively. The occasional insertion of a 256MiB buffer into the `sync.Pool` gets continually held by the 1KiB routines. On my machine, after 300 GC cycles, the above program occupies 6GiB of my heap, when I expect it to be 256MiB in the worst-case.\r\n\r\n\\cc @jnjackins @bradfitz "