#15912: pretty print too slow with long lists
-------------------------+-------------------------------------------------
Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.2
Component: | Keywords: pretty, output, lists,
performance | factorial
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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Assume a student who, in a mood of serendipity, plays with Sage. While
both pari and Sage use on the order of 10ms to compute the divisors of
20!:
{{{
? divisors(20!)
sage: divisors(Integer(20).factorial())
}}}
the actual time for screen output is much different, where I would
estimate pari with less than 100ms but Sage with about 2.5 sec in a
terminal on a 3GHz machine. The list has 41040 entries. Sage seems to
buffer the stuff somewhere before actual output, and this appears to take
a lot of CPU.
You can imagine what happens with 30! where both Sage and pari need 1-2
sec for computation. I had to interrupt Sage after a minute to see this
backtrace:
{{{
/home/ralf/sage/local/lib/python2.7/site-
packages/IPython/core/displayhook.pyc in __call__(self, result)
236 self.start_displayhook()
237 self.write_output_prompt()
--> 238 format_dict = self.compute_format_data(result)
239 self.write_format_data(format_dict)
240 self.update_user_ns(result)
/home/ralf/sage/local/lib/python2.7/site-
packages/IPython/core/displayhook.pyc in compute_format_data(self, result)
148 MIME type representation of the object.
149 """
--> 150 return self.shell.display_formatter.format(result)
151
152 def write_format_data(self, format_dict):
/home/ralf/sage/local/lib/python2.7/site-
packages/IPython/core/formatters.pyc in format(self, obj, include,
exclude)
124 continue
125 try:
--> 126 data = formatter(obj)
127 except:
128 # FIXME: log the exception
/home/ralf/sage/local/lib/python2.7/site-
packages/sage/misc/displayhook.pyc in __call__(self, obj)
508 s = self.try_format_obj(obj)
509 if s is None:
--> 510 s = super(SagePlainTextFormatter, self).__call__(obj)
511 return s
512
/home/ralf/sage/local/lib/python2.7/site-
packages/IPython/core/formatters.pyc in __call__(self, obj)
445 type_pprinters=self.type_printers,
446 deferred_pprinters=self.deferred_printers)
--> 447 printer.pretty(obj)
448 printer.flush()
449 return stream.getvalue()
/home/ralf/sage/local/lib/python2.7/site-packages/IPython/lib/pretty.pyc
in pretty(self, obj)
343 if cls in self.type_pprinters:
344 # printer registered in self.type_pprinters
--> 345 return self.type_pprinters[cls](obj, self,
cycle)
346 else:
347 # deferred printer
/home/ralf/sage/local/lib/python2.7/site-packages/IPython/lib/pretty.pyc
in inner(obj, p, cycle)
527 p.text(',')
528 p.breakable()
--> 529 p.pretty(x)
530 if len(obj) == 1 and type(obj) is tuple:
531 # Special case for 1-item tuples.
/home/ralf/sage/local/lib/python2.7/site-packages/IPython/lib/pretty.pyc
in pretty(self, obj)
346 else:
347 # deferred printer
--> 348 printer = self._in_deferred_types(cls)
349 if printer is not None:
350 return printer(obj, self, cycle)
/home/ralf/sage/local/lib/python2.7/site-packages/IPython/lib/pretty.pyc
in _in_deferred_types(self, cls)
372 """
373 mod = getattr(cls, '__module__', None)
--> 374 name = getattr(cls, '__name__', None)
375 key = (mod, name)
376 printer = None
/home/ralf/sage/local/lib/python2.7/site-packages/sage/ext/c_lib.so in
sage.ext.c_lib.sage_python_check_interrupt (sage/ext/c_lib.c:1634)()
/home/ralf/sage/local/lib/python2.7/site-packages/sage/ext/c_lib.so in
sage.ext.c_lib.sig_raise_exception (sage/ext/c_lib.c:835)()
KeyboardInterrupt:
}}}
The student was not exactly encouraged to continue using Sage.
--
Ticket URL: <http://trac.sagemath.org/ticket/15912>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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