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tty: use blocking mode on OS X #6895

Merged
merged 2 commits into from
Jun 1, 2016
Merged

tty: use blocking mode on OS X #6895

merged 2 commits into from
Jun 1, 2016

Commits on Jun 1, 2016

  1. tty: use blocking mode on OS X 

    OS X has a tiny 1kb hard-coded buffer size for stdout / stderr to
TTYs (terminals). Output larger than that causes chunking, which ends
up having some (very small but existent) delay past the first chunk.
That causes two problems:

1. When output is written to stdout and stderr at similar times, the
two can become mixed together (interleaved). This is especially
problematic when using control characters, such as \r. With
interleaving, chunked output will often have lines or characters erased
unintentionally, or in the wrong spots, leading to broken output.
CLI apps often extensively use such characters for things such as
progress bars.

2. Output can be lost if the process is exited before chunked writes
are finished flushing. This usually happens in applications that use
`process.exit()`, which isn't infrequent.

See nodejs#6980 for more info.

This became an issue as result of the Libuv 1.9.0 upgrade. A fix to
an unrelated issue broke a hack previously required for the OS X
implementation. This resulted in an unexpected behavior change in node.
The 1.9.0 upgrade was done in c3cec1e,
which was included in v6.0.0.
Full details of the Libuv issue that induced this are at
nodejs#6456 (comment)

Refs: nodejs#1771
Refs: nodejs#6456
Refs: nodejs#6773
Refs: nodejs#6816
PR-URL: nodejs#6895
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
    @Fishrock123
    Fishrock123 committed Jun 1, 2016
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  2. test: test TTY problems by fakeing a TTY using openpty 

    Many thanks to thefourtheye and addaleax who helped make the python
bits of this possible.

See nodejs#6980 for more info regarding
the related TTY issues.

Refs: nodejs#6456
Refs: nodejs#6773
Refs: nodejs#6816
PR-URL: nodejs#6895
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
    @Fishrock123
    Fishrock123 committed Jun 1, 2016
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    88804b8 View commit details
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