mirror of https://github.com/python/cpython
75 lines
2.7 KiB
Plaintext
75 lines
2.7 KiB
Plaintext
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The Python Profiler
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To use the profiler in its simplest form:
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>>> import profile
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>>> profile.run(statement)
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This will execute the statement and print statistics. To get more
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information out of the profiler, use:
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>>> import profile
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>>> profile.run(statement, dump_file)
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where dump_file is a string naming a file to which the (binary)
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profile statistics is to be dumped. The binary format is a dump of a
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dictionary. The key is the function name in the format described
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above; the value is a tuple consisting of, in order, number of calls,
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total time spent in the function, total time spent in the function and
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all functions called from it, a list of functions called by this
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function, and a list of functions that called this function. The dump
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can be read back using the following code:
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>>> import marshal
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>>> f = open(dump_file, 'r')
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>>> dict = marshal.load(f)
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>>> f.close()
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An easier way of doing this is by using the class `Stats' which is
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also defined in profile:
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>>> import profile
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>>> s = profile.Stats().init(dump_file)
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The following methods are defined for instances of `Stats':
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print_stats() -- Print the statistics in a format similar to
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the format profile.run() uses.
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print_callers() -- For each function, print all functions
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which it calls.
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print_callees() -- For each function, print all functions from
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which it is called.
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sort_stats(n) -- Sort the statistics for subsequent
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printing. The argument determines on which
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field the output should be sorted.
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Possibilities are
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-1 function name
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0 number of calls
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1 total time spent in a function
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2 total time spent in a function
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plus all functions it called
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strip_dirs() -- Strip the directory names off of the file
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names which are part of the function names.
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This undoes the effect of sort_stats(), but
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a subsequent sort_stats() does work.
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The methods sort_stats and strip_dirs may change in the future.
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Output of profile.run(statement) and of the print_stats() method of
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the `Stats' class consists of the following fields.
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Number of times the function was called.
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Total time spent in the function.
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Mean time per function call (second field divided by first).
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Total time spent in the function and all functions it called,
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recursively.
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Mean time time spent in the function and all functions it
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called (fourth field divided by first).
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Name of the function in the format
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<file name>:<line number>(<function name>)
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The output of the print_callers and print_callees methods consists of
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the name of the function and the names of all function it called or
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was called from. The latter names are followed by a parenthesised
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number which is the number of calls for this function.
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