| commit | 97d0505334c71a8d7a1e7431c1e1515c93b59e2b | [log] [tgz] |
|---|---|---|
| author | Carlo Alberto Ferraris <cafxx@strayorange.com> | Sat Oct 26 16:26:59 2019 +0900 |
| committer | Keith Randall <khr@golang.org> | Tue Nov 12 21:40:12 2019 +0000 |
| tree | 3f0655d443c537546431c06cbf9a5862d02a5bb7 | |
| parent | 2de897f4807aa552c5d223e0744c9624fa498d48 [diff] |
runtime: consistently seed fastrand state across archs Some, but not all, architectures mix in OS-provided random seeds when initializing the fastrand state. The others have TODOs saying we need to do the same. Lift that logic up in the architecture-independent part, and use memhash to mix the seed instead of a simple addition. Previously, dumping the fastrand state at initialization would yield something like the following on linux-amd64, where the values in the first column do not change between runs (as thread IDs are sequential and always start at 0), and the values in the second column, while changing every run, are pretty correlated: first run: 0x0 0x44d82f1c 0x5f356495 0x44f339de 0xbe6ac92a 0x44f91cd8 0x1da02dbf 0x44fd91bc 0x7cd59254 0x44fee8a4 0xdc0af6e9 0x4547a1e0 0x3b405b7e 0x474c76fc 0x9a75c013 0x475309dc 0xf9ab24a8 0x4bffd075 second run: 0x0 0xa63fc3eb 0x5f356495 0xa6648dc2 0xbe6ac92a 0xa66c1c59 0x1da02dbf 0xa671bce8 0x7cd59254 0xa70e8287 0xdc0af6e9 0xa7129d2e 0x3b405b7e 0xa7379e2d 0x9a75c013 0xa7e4c64c 0xf9ab24a8 0xa7ecce07 With this change, we get initial states that appear to be much more unpredictable, both within the same run as well as between runs: 0x11bddad7 0x97241c63 0x553dacc6 0x2bcd8523 0x62c01085 0x16413d92 0x6f40e9e6 0x7a138de6 0xa4898053 0x70d816f0 0x5ca5b433 0x188a395b 0x62778ca9 0xd462c3b5 0xd6e160e4 0xac9b4bd 0xb9571d65 0x597a981d Change-Id: Ib22c530157d74200df0083f830e0408fd4aaea58 Reviewed-on: https://go-review.googlesource.com/c/go/+/203439 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
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