How to Contribute Go

Go Conference 2016 Spring

Transcript

1. How to 

   Contribute Go
   Hatena Co., Ltd.
   Shinji Tanaka @stanaka
   

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2. Shinji Tanaka
   @stanaka / id:stanaka
   Hatena Co., Ltd. CTO
   2
   

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3. One day, a tool couldn’t start
   • only on Amazon Linux 2016.03
   $ some-tool (linux/386 build)
   Trace/breakpoint trap
   $
   

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4. >> Trace/breakpoint trap <<
   

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5. modify_ldt
   • System call called at the boot
   process of Go 386 binary.
   • Disabled on Amazon Linux 2016.04
   $ cat /boot/config-4.4.5-15.26.amzn1.x86_64 \
   | grep MODIFY_LDT
   # CONFIG_MODIFY_LDT_SYSCALL is not set
   https://github.com/golang/go/issues/14795
   

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6. Die or Contribute
   • O.K. Let’s contribute.
   

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7. How to fix it (partial diff)
   https://github.com/golang/go/commit/
   0f86d1edfb87fddb2c7f50d177b67f48219151f3
   

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8. Go’s Assembler
   • It’s like a Plan-9 assembler
   TEXT runtime·profileloop(SB),NOSPLIT,$8
   MOVQ $runtime·profileloop1(SB), CX
   MOVQ CX, 0(SP)
   CALL runtime·externalthreadhandler(SB)
   RET
   

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9. Merged!!
   

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10. Go contribute
    Outline
    

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11. Contribution Guidelines
    IUUQTHPMBOHPSHEPDDPOUSJCVUFIUNM
    

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12. File an Issues on GitHub
    • https://github.com/golang/go/issues/14795
    

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13. git codereview
    • Subcommand of git for Go code
    review.
    git codereview change
    git codereview mail
    git codereview …
    [alias]
    change = codereview change
    gofmt = codereview gofmt
    mail = codereview mail
    pending = codereview pending
    submit = codereview submit
    sync = codereview sync
    

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14. git codereview change
    • Make a change on some branch
    • Same as
    git codereview change
    git checkout -b branch
    git branch --set-upstream-to origin/master
    git commit
    

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15. Detailed commit message
    runtime: use set_thread_area instead of modify_ldt on linux/386
    linux/386 depends on modify_ldt system call, but recent Linux kernels can disable this
    system call. Any Go programs built as linux/386 crash with the message 'Trace/
    breakpoint trap'.
    The kernel config CONFIG_MODIFY_LDT_SYSCALL, which control enable/disable
    modify_ldt, is disabled on Amazon Linux 2016.03.
    This fixes this problem by using set_thread_area instead of modify_ldt on linux/386.
    Fixes #14795.
    

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16. git codereview mail
    • Push to go-review
    • Same as
    git codereview mail
    git push origin HEAD:refs/for/master.
    

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17. Revise the commit
    • change & mail again
    

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18. Gerrit
    https://go-review.googlesource.com/
    

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19. Code reviewing #1
    

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20. Code reviewing #2
    

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21. Save as Draft & Reply
    

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22. Merged!!
    • ‘Code-Review +2’ is required.
    • +2 approved
    • +1 LGTM, but not approved
    • Maybe this fix released with Go 1.7?
    

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23. Let’s Contribute Go
    We’re hiring
    

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