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Ops is seeing duplicate UUID's being generated from multiple sandboxes #87

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trink opened this issue Apr 29, 2015 · 3 comments
Closed

Ops is seeing duplicate UUID's being generated from multiple sandboxes #87

trink opened this issue Apr 29, 2015 · 3 comments

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@trink
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trink commented Apr 29, 2015

There are a few issues:

  1. between separate processes (they most likely used the same seed, since it is just time_t). A better seed should be used.
  2. srand/rand are not thread safe in C so the behaviour probably isn't matching expectations
    2a) the Lua math library uses srand/rand so it should also be addressed there.
  3. the modulo operation does not generate uniformly distributed random numbers in the span (lower numbers are slightly more likely).
@trink
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trink commented Apr 29, 2015

Digging: glibc has a lock around it so comment 2 should not be a problem for the Ops deploy
https://sourceware.org/git/?p=glibc.git;a=blob;f=stdlib/rand.c;hb=glibc-2.15#l26
https://sourceware.org/git/?p=glibc.git;a=blob;f=stdlib/random.c;hb=glibc-2.15#l292

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trink commented Apr 29, 2015

@whd was the duplication between processes or within a process?

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trink commented May 11, 2015

Closed via #88

@trink trink closed this as completed May 11, 2015
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