e.printStackTrace equivalent in python
In Java, this does the following (docs):
public void printStackTrace()Prints this throwable and its backtrace to the standard error stream...
This is used like this:
try
{
// code that may raise an error
}
catch (IOException e)
{
// exception handling
e.printStackTrace();
}
In Java, the Standard Error stream is unbuffered so that output arrives immediately.
import traceback
import sys
try: # code that may raise an error
pass
except IOError as e: # exception handling
# in Python 2, stderr is also unbuffered
print >> sys.stderr, traceback.format_exc()
# in Python 2, you can also from __future__ import print_function
print(traceback.format_exc(), file=sys.stderr)
# or as the top answer here demonstrates, use:
traceback.print_exc()
# which also uses stderr.
In Python 3, we can get the traceback directly from the exception object (which likely behaves better for threaded code). Also, stderr is line-buffered, but the print function gets a flush argument, so this would be immediately printed to stderr:
print(traceback.format_exception(None, # <- type(e) by docs, but ignored
e, e.__traceback__),
file=sys.stderr, flush=True)
Conclusion:
In Python 3, therefore, traceback.print_exc(), although it uses sys.stderr by default, would buffer the output, and you may possibly lose it. So to get as equivalent semantics as possible, in Python 3, use print with flush=True.