Why compile Python code

Question

Why would you compile a Python script  You can run them directly from the  py file and it works fine  so is there a performance advantage or something    I also notice that some files in my application get compiled into  pyc while others do not  why is this

User · Answer

The  pyc file is Python that has already been compiled to byte-code   Python automatically runs a  pyc file if it finds one with the same name as a  py file you invoke    An Introduction to Python  says this about compiled Python files      A program doesn t run any faster when   it is read from a     pyc    or     pyo      file than when it is read from a     py      file  the only thing that s faster   about     pyc    or     pyo    files is the   speed with which they are loaded    The advantage of running a  pyc file is that Python doesn t have to incur the overhead of compiling it before running it   Since Python would compile to byte-code before running a  py file anyway  there shouldn t be any performance improvement aside from that   How much improvement can you get from using compiled  pyc files   That depends on what the script does   For a very brief script that simply prints  Hello World   compiling could constitute a large percentage of the total startup-and-run time   But the cost of compiling a script relative to the total run time diminishes for longer-running scripts   The script you name on the command-line is never saved to a  pyc file  Only modules loaded by that  main  script are saved in that way

User · Answer

As already mentioned  you can get a performance increase from having your python code compiled into bytecode  This is usually handled by python itself  for imported scripts only   Another reason you might want to compile your python code  could be to protect your intellectual property from being copied and or modified   You can read more about this in the Python documentation

User · Answer

There s certainly a performance difference when running a compiled script  If you run normal  py scripts  the machine compiles it every time it is run and this takes time  On modern machines this is hardly noticeable but as the script grows it may become more of an issue

User · Answer

There s certainly a performance difference when running a compiled script  If you run normal  py scripts  the machine compiles it every time it is run and this takes time  On modern machines this is hardly noticeable but as the script grows it may become more of an issue

User · Answer

Beginners assume Python is compiled because of  pyc files  The  pyc file is the compiled bytecode  which is then interpreted  So if you ve run your Python code before and have the  pyc file handy  it will run faster the second time  as it doesn t have to re-compile the bytecode  compiler      A compiler is a piece of code that translates the high level language into machine language  Interpreters  Interpreters also convert the high level language into machine readable binary equivalents  Each time when an interpreter gets a high level language code to be executed  it converts the code into an intermediate code before converting it into the machine code  Each part of the code is interpreted and then execute separately in a sequence and an error is found in a part of the code it will stop the interpretation of the code without translating the next set of the codes     Sources  http   www toptal com python why-are-there-so-many-pythons http   www engineersgarage com contribution difference-between-compiler-and-interpreter

User · Answer

There is a performance increase in running compiled python  However when you run a  py file as an imported module  python will compile and store it  and as long as the  py file does not change it will always use the compiled version   With any interpeted language when the file is used the process looks something like this  1  File is processed by the interpeter  2  File is compiled 3  Compiled code is executed   obviously by using pre-compiled code you can eliminate step 2  this applies python  PHP and others   Heres an interesting blog post explaining the differences http   julipedia blogspot com 2004 07 compiled-vs-interpreted-languages html And here s an entry that explains the Python compile process http   effbot org zone python-compile htm

User · Answer

Yep  performance is the main reason and  as far as I know  the only reason   If some of your files aren t getting compiled  maybe Python isn t able to write to the  pyc file  perhaps because of the directory permissions or something   Or perhaps the uncompiled files just aren t ever getting loaded     scripts modules only get compiled when they first get loaded

User · Answer

As already mentioned  you can get a performance increase from having your python code compiled into bytecode  This is usually handled by python itself  for imported scripts only   Another reason you might want to compile your python code  could be to protect your intellectual property from being copied and or modified   You can read more about this in the Python documentation

User · Answer

It s compiled to bytecode which can be used much  much  much faster   The reason some files aren t compiled is that the main script  which you invoke with python main py is recompiled every time you run the script  All imported scripts will be compiled and stored on the disk   Important addition by Ben Blank      It s worth noting that while running a   compiled script has a faster startup   time  as it doesn t need to be   compiled   it doesn t run any   faster

User · Answer

There is a performance increase in running compiled python  However when you run a  py file as an imported module  python will compile and store it  and as long as the  py file does not change it will always use the compiled version   With any interpeted language when the file is used the process looks something like this  1  File is processed by the interpeter  2  File is compiled 3  Compiled code is executed   obviously by using pre-compiled code you can eliminate step 2  this applies python  PHP and others   Heres an interesting blog post explaining the differences http   julipedia blogspot com 2004 07 compiled-vs-interpreted-languages html And here s an entry that explains the Python compile process http   effbot org zone python-compile htm

User · Answer

There s certainly a performance difference when running a compiled script  If you run normal  py scripts  the machine compiles it every time it is run and this takes time  On modern machines this is hardly noticeable but as the script grows it may become more of an issue

User · Answer

The  pyc file is Python that has already been compiled to byte-code   Python automatically runs a  pyc file if it finds one with the same name as a  py file you invoke    An Introduction to Python  says this about compiled Python files      A program doesn t run any faster when   it is read from a     pyc    or     pyo      file than when it is read from a     py      file  the only thing that s faster   about     pyc    or     pyo    files is the   speed with which they are loaded    The advantage of running a  pyc file is that Python doesn t have to incur the overhead of compiling it before running it   Since Python would compile to byte-code before running a  py file anyway  there shouldn t be any performance improvement aside from that   How much improvement can you get from using compiled  pyc files   That depends on what the script does   For a very brief script that simply prints  Hello World   compiling could constitute a large percentage of the total startup-and-run time   But the cost of compiling a script relative to the total run time diminishes for longer-running scripts   The script you name on the command-line is never saved to a  pyc file  Only modules loaded by that  main  script are saved in that way

User · Answer

Something not touched upon is source-to-source-compiling  For example  nuitka translates Python code to C C    and compiles it to binary code which directly runs on the CPU  instead of Python bytecode which runs on the slower virtual machine   This can lead to significant speedups  or it would let you work with Python while your environment depends on C C   code

User · Answer

It s compiled to bytecode which can be used much  much  much faster   The reason some files aren t compiled is that the main script  which you invoke with python main py is recompiled every time you run the script  All imported scripts will be compiled and stored on the disk   Important addition by Ben Blank      It s worth noting that while running a   compiled script has a faster startup   time  as it doesn t need to be   compiled   it doesn t run any   faster

User · Answer

We use compiled code to distribute to users who do not have access to the source code  Basically to stop inexperienced programers accidentally changing something or fixing bugs without telling us

User · Answer

As already mentioned  you can get a performance increase from having your python code compiled into bytecode  This is usually handled by python itself  for imported scripts only   Another reason you might want to compile your python code  could be to protect your intellectual property from being copied and or modified   You can read more about this in the Python documentation

User · Answer

There s certainly a performance difference when running a compiled script  If you run normal  py scripts  the machine compiles it every time it is run and this takes time  On modern machines this is hardly noticeable but as the script grows it may become more of an issue

User · Answer

There is a performance increase in running compiled python  However when you run a  py file as an imported module  python will compile and store it  and as long as the  py file does not change it will always use the compiled version   With any interpeted language when the file is used the process looks something like this  1  File is processed by the interpeter  2  File is compiled 3  Compiled code is executed   obviously by using pre-compiled code you can eliminate step 2  this applies python  PHP and others   Heres an interesting blog post explaining the differences http   julipedia blogspot com 2004 07 compiled-vs-interpreted-languages html And here s an entry that explains the Python compile process http   effbot org zone python-compile htm

User · Answer

Yep  performance is the main reason and  as far as I know  the only reason   If some of your files aren t getting compiled  maybe Python isn t able to write to the  pyc file  perhaps because of the directory permissions or something   Or perhaps the uncompiled files just aren t ever getting loaded     scripts modules only get compiled when they first get loaded

User · Answer

Pluses   First  mild  defeatable obfuscation   Second  if compilation results in a significantly smaller file  you will get faster load times  Nice for the web   Third  Python can skip the compilation step  Faster at intial load  Nice for the CPU and the web   Fourth  the more you comment  the smaller the  pyc or  pyo file will be in comparison to the source  py file   Fifth  an end user with only a  pyc or  pyo file in hand is much less likely to present you with a bug they caused by an un-reverted change they forgot to tell you about   Sixth  if you re aiming at an embedded system  obtaining a smaller size file to embed may represent a significant plus  and the architecture is stable so drawback one  detailed below  does not come into play   Top level compilation  It is useful to know that you can compile a top level python source file into a  pyc file this way   python -m py compile myscript py   This removes comments  It leaves docstrings intact  If you d like to get rid of the docstrings as well  you might want to seriously think about why you re doing that  then compile this way instead     python -OO -m py compile myscript py      and you ll get a  pyo file instead of a  pyc file  equally distributable in terms of the code s essential functionality  but smaller by the size of the stripped-out docstrings  and less easily understood for subsequent employment if it had decent docstrings in the first place   But see drawback three  below   Note that python uses the  py file s date  if it is present  to decide whether it should execute the  py file as opposed to the  pyc or  pyo file --- so edit your  py file  and the  pyc or  pyo is obsolete and whatever benefits you gained are lost  You need to recompile it in order to get the  pyc or  pyo benefits back again again  such as they may be   Drawbacks   First  There s a  magic cookie  in  pyc and  pyo files that indicates the system architecture that the python file was compiled in  If you distribute one of these files into an environment of a different type  it will break  If you distribute the  pyc or  pyo without the associated  py to recompile or touch so it supersedes the  pyc or  pyo  the end user can t fix it  either   Second  If docstrings are skipped with the use of the -OO command line option as described above  no one will be able to get at that information  which can make use of the code more difficult  or impossible    Third  Python s -OO option also implements some optimizations as per the -O command line option  this may result in changes in operation  Known optimizations are    sys flags optimize   1 assert statements are skipped   debug     False   Fourth  if you had intentionally made your python script executable with something on the order of    usr bin python on the first line  this is stripped out in  pyc and  pyo files and that functionality is lost   Fifth  somewhat obvious  but if you compile your code  not only can its use be impacted  but the potential for others to learn from your work is reduced  often severely

User · Answer

The  pyc file is Python that has already been compiled to byte-code   Python automatically runs a  pyc file if it finds one with the same name as a  py file you invoke    An Introduction to Python  says this about compiled Python files      A program doesn t run any faster when   it is read from a     pyc    or     pyo      file than when it is read from a     py      file  the only thing that s faster   about     pyc    or     pyo    files is the   speed with which they are loaded    The advantage of running a  pyc file is that Python doesn t have to incur the overhead of compiling it before running it   Since Python would compile to byte-code before running a  py file anyway  there shouldn t be any performance improvement aside from that   How much improvement can you get from using compiled  pyc files   That depends on what the script does   For a very brief script that simply prints  Hello World   compiling could constitute a large percentage of the total startup-and-run time   But the cost of compiling a script relative to the total run time diminishes for longer-running scripts   The script you name on the command-line is never saved to a  pyc file  Only modules loaded by that  main  script are saved in that way

User · Answer

Pluses   First  mild  defeatable obfuscation   Second  if compilation results in a significantly smaller file  you will get faster load times  Nice for the web   Third  Python can skip the compilation step  Faster at intial load  Nice for the CPU and the web   Fourth  the more you comment  the smaller the  pyc or  pyo file will be in comparison to the source  py file   Fifth  an end user with only a  pyc or  pyo file in hand is much less likely to present you with a bug they caused by an un-reverted change they forgot to tell you about   Sixth  if you re aiming at an embedded system  obtaining a smaller size file to embed may represent a significant plus  and the architecture is stable so drawback one  detailed below  does not come into play   Top level compilation  It is useful to know that you can compile a top level python source file into a  pyc file this way   python -m py compile myscript py   This removes comments  It leaves docstrings intact  If you d like to get rid of the docstrings as well  you might want to seriously think about why you re doing that  then compile this way instead     python -OO -m py compile myscript py      and you ll get a  pyo file instead of a  pyc file  equally distributable in terms of the code s essential functionality  but smaller by the size of the stripped-out docstrings  and less easily understood for subsequent employment if it had decent docstrings in the first place   But see drawback three  below   Note that python uses the  py file s date  if it is present  to decide whether it should execute the  py file as opposed to the  pyc or  pyo file --- so edit your  py file  and the  pyc or  pyo is obsolete and whatever benefits you gained are lost  You need to recompile it in order to get the  pyc or  pyo benefits back again again  such as they may be   Drawbacks   First  There s a  magic cookie  in  pyc and  pyo files that indicates the system architecture that the python file was compiled in  If you distribute one of these files into an environment of a different type  it will break  If you distribute the  pyc or  pyo without the associated  py to recompile or touch so it supersedes the  pyc or  pyo  the end user can t fix it  either   Second  If docstrings are skipped with the use of the -OO command line option as described above  no one will be able to get at that information  which can make use of the code more difficult  or impossible    Third  Python s -OO option also implements some optimizations as per the -O command line option  this may result in changes in operation  Known optimizations are    sys flags optimize   1 assert statements are skipped   debug     False   Fourth  if you had intentionally made your python script executable with something on the order of    usr bin python on the first line  this is stripped out in  pyc and  pyo files and that functionality is lost   Fifth  somewhat obvious  but if you compile your code  not only can its use be impacted  but the potential for others to learn from your work is reduced  often severely

User · Answer

It s compiled to bytecode which can be used much  much  much faster   The reason some files aren t compiled is that the main script  which you invoke with python main py is recompiled every time you run the script  All imported scripts will be compiled and stored on the disk   Important addition by Ben Blank      It s worth noting that while running a   compiled script has a faster startup   time  as it doesn t need to be   compiled   it doesn t run any   faster

User · Answer

As already mentioned  you can get a performance increase from having your python code compiled into bytecode  This is usually handled by python itself  for imported scripts only   Another reason you might want to compile your python code  could be to protect your intellectual property from being copied and or modified   You can read more about this in the Python documentation

User · Answer

It s compiled to bytecode which can be used much  much  much faster   The reason some files aren t compiled is that the main script  which you invoke with python main py is recompiled every time you run the script  All imported scripts will be compiled and stored on the disk   Important addition by Ben Blank      It s worth noting that while running a   compiled script has a faster startup   time  as it doesn t need to be   compiled   it doesn t run any   faster

User · Answer

There is a performance increase in running compiled python  However when you run a  py file as an imported module  python will compile and store it  and as long as the  py file does not change it will always use the compiled version   With any interpeted language when the file is used the process looks something like this  1  File is processed by the interpeter  2  File is compiled 3  Compiled code is executed   obviously by using pre-compiled code you can eliminate step 2  this applies python  PHP and others   Heres an interesting blog post explaining the differences http   julipedia blogspot com 2004 07 compiled-vs-interpreted-languages html And here s an entry that explains the Python compile process http   effbot org zone python-compile htm

User · Answer

Something not touched upon is source-to-source-compiling  For example  nuitka translates Python code to C C    and compiles it to binary code which directly runs on the CPU  instead of Python bytecode which runs on the slower virtual machine   This can lead to significant speedups  or it would let you work with Python while your environment depends on C C   code

User · Answer

We use compiled code to distribute to users who do not have access to the source code  Basically to stop inexperienced programers accidentally changing something or fixing bugs without telling us

User · Answer

Beginners assume Python is compiled because of  pyc files  The  pyc file is the compiled bytecode  which is then interpreted  So if you ve run your Python code before and have the  pyc file handy  it will run faster the second time  as it doesn t have to re-compile the bytecode  compiler      A compiler is a piece of code that translates the high level language into machine language  Interpreters  Interpreters also convert the high level language into machine readable binary equivalents  Each time when an interpreter gets a high level language code to be executed  it converts the code into an intermediate code before converting it into the machine code  Each part of the code is interpreted and then execute separately in a sequence and an error is found in a part of the code it will stop the interpretation of the code without translating the next set of the codes     Sources  http   www toptal com python why-are-there-so-many-pythons http   www engineersgarage com contribution difference-between-compiler-and-interpreter

User · Answer

The  pyc file is Python that has already been compiled to byte-code   Python automatically runs a  pyc file if it finds one with the same name as a  py file you invoke    An Introduction to Python  says this about compiled Python files      A program doesn t run any faster when   it is read from a     pyc    or     pyo      file than when it is read from a     py      file  the only thing that s faster   about     pyc    or     pyo    files is the   speed with which they are loaded    The advantage of running a  pyc file is that Python doesn t have to incur the overhead of compiling it before running it   Since Python would compile to byte-code before running a  py file anyway  there shouldn t be any performance improvement aside from that   How much improvement can you get from using compiled  pyc files   That depends on what the script does   For a very brief script that simply prints  Hello World   compiling could constitute a large percentage of the total startup-and-run time   But the cost of compiling a script relative to the total run time diminishes for longer-running scripts   The script you name on the command-line is never saved to a  pyc file  Only modules loaded by that  main  script are saved in that way

User · Answer

Yep  performance is the main reason and  as far as I know  the only reason   If some of your files aren t getting compiled  maybe Python isn t able to write to the  pyc file  perhaps because of the directory permissions or something   Or perhaps the uncompiled files just aren t ever getting loaded     scripts modules only get compiled when they first get loaded

User · Answer

Yep  performance is the main reason and  as far as I know  the only reason   If some of your files aren t getting compiled  maybe Python isn t able to write to the  pyc file  perhaps because of the directory permissions or something   Or perhaps the uncompiled files just aren t ever getting loaded     scripts modules only get compiled when they first get loaded

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