98286e9850 made it so that
`Module#include` allocates an origin iclass on each use. Since `include`
is widely used, the extra allocation can contribute significantly to
memory usage.
Instead of always allocating in anticipation of prepend, this change
takes a different approach. The new setup inserts a origin iclass into
the super chains of all the children of the module when prepend happens
for the first time.
rb_ensure_origin is made static again since now that adding an origin
now means walking over all usages, we want to limit the number of places
where we do it.
The RubyVM uses C macro defines to feature detect whether
`backtrace(2)` support is available, and if so it includes C level backtraces
when the RubyVM itself crashes.
But on my machine, C level backtraces from `vm_dump.c` didn't work when
using a version of Ruby buillt on the machine, but worked fine when using a
version of Ruby built on another machine and copied to my machine.
The default autoconf test for backtraces uses a sigaltstack size that is
too small, so the SIGSEGV signal handler itself causes a SIGSEGV).
I noticed that signal.c uses a larger sigaltstack size:
https://github.com/ruby/ruby/blob/v2_6_5/signal.c#L568
The specific variables it looks at:
- `HAVE_BACKTRACE`
this is a macro defined by autoconf because there is a line in the
configure script like `AC_CHECK_FUNCS(backtrace)` (see the autoconf
docs for more).
- `BROKEN_BACKTRACE`
this comes from a custom program that Ruby's configure script runs to
attempt to figure out whether actually using backtrace(2) in a real
program works. You can see the autoconf program here.
<https://github.com/ruby/ruby/blob/v2_6_5/configure.ac#L2817-L2863>
It uses sigaltstack and SA_ONSTACK to create a seperate stack for
handling signals.
The problem was: SIGSTKSZ (which comes from a system header!) was not
suggesting a large enough stack size. When checking on an Ubuntu 16.04
box, we found that SIGSTKSZ was 8192 and MINSIGSTKSZ was 2048.
nobu-san reviewed,
https://github.com/ruby/irb/pull/106#pullrequestreview-423400033
> How about lexer = Ripper::Lexer.new(";\n#{code}", nil, 0)?
> Encoding pragma is effective only at the beginning.
> And the semicolon and newline will be skipped because the position is before
> the initial pos.
I employ the way.
Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
e593cc65b7
* fraction -> subsecond
for consistency with method name
* The sentence,
"A non-portable feature allows the offset to be negative on some systems.",
is removed.
Time before 1970 should work portably now.
If localtime() doesn't work before 1970,
Ruby should extrapolate it.
* Time::new -> Time.new
"::" for method call is not common notation now.
* Time#to_i truncates subsecond
* Time#to_f approximates a value in Time object
* Time#to_r
The sentence,
"You can use this method to convert _time_ to another Epoch.",
is removed.
It is not clear because no actual example of "another Epoch" is given.
* Time#usec truncates fraction of microseconds.
* Time#nsec truncates fraction of nanoseconds.
* describe Time#inspect shows subsecond since Ruby 2.7.0.
