Using DTrace-enabled Python in a Joyent Accelerator

Bryan wrote about a presentation he gave at Google (video) where he demo’ed DTrace in Python. While we did the dtrace probes for Ruby 1.8.5 and 1.8.6, I thought I’d show you how to do it on our Accelerators as well.

John Levon at Sun has written about the DTrace probes that he put into Python 2.4 before. So we have somewhere to start.

Let’s get Python 2.4.4 and the DTrace patch

mkdir /a/src/
mkdir /a/1/languages/python244d
curl -O http://python.org/ftp/python/2.4.4/Python-2.4.4.tgz
tar zxvf Python-2.4.4.tgz
curl -O http://cvs.opensolaris.org/source/xref//jds/spec-files/trunk/patches/Python-07-dtrace.diff

The patch expects a directory call Python-new, so let’s create it

cp -R Python-2.4.4 Python-new

Let’s now apply the patch

gpatch -p0 < Python-07-dtrace.diff

The output of this working looks like

patching file Python-new/Include/frameobject.h
patching file Python-new/Makefile.pre.in
patching file Python-new/Objects/frameobject.c
patching file Python-new/Python/ceval.c
patching file Python-new/Python/phelper.d
patching file Python-new/Python/python.d

Move on in

cd Python-new/

Run configure

./configure --prefix=/a/1/languages/python244d --enable-shared

Now there’s going to be a couple of changes we’re going to make here so the thing builds, because if you type make && make install right now, it’ll fail. First in one way and then when you fix that, another.

Basically we have to bring the patch and Makefile up so that it’s a full 64-bit build (what our gcc compilers default to.

Open up the ustack helper file

nano Python/phelper.d

And take a look right at the top:

#define _SYS_STAT_H
#include < stdio.h >
#include "pyport.h"

And under the #include , add the two lines below

#define _SYS_STAT_H
#include < stdio.h >
#include < sys/socket.h >
#include < sys/socketvar.h >
#include "pyport.h"

Now the makefile

# Compiler options
OPT=            -DNDEBUG -g -O3 -Wall -Wstrict-prototypes
BASECFLAGS=      -fno-strict-aliasing
CFLAGS=         $(BASECFLAGS) $(OPT)
CPPFLAGS=       -I. -I$(srcdir)/Include
LDFLAGS=
LDLAST=
SGI_ABI=
CCSHARED=       -fPIC
LINKFORSHARED=

Add the -m64 flag to LDFLAGS

# Compiler options
OPT=            -DNDEBUG -g -O3 -Wall -Wstrict-prototypes
BASECFLAGS=      -fno-strict-aliasing
CFLAGS=         $(BASECFLAGS) $(OPT)
CPPFLAGS=       -I. -I$(srcdir)/Include
LDFLAGS=        -m64
LDLAST=
SGI_ABI=
CCSHARED=       -fPIC
LINKFORSHARED=

And finally we’ll add a -64 flag to each of the dtrace compile lines, so that you’re doing a 64-bit build all the way around.

So lines like

dtrace -o $@ -DPHELPER $(DFLAGS) $(CPPFLAGS) -C -G -s $(srcdir)/Python/phelper.d

Become

# grep dtrace Makefile
DTRACE_OBJS=Python/dtrace.o Python/phelper.o
        dtrace -o $@ -DPHELPER $(DFLAGS) $(CPPFLAGS) -C -G -64 -s $(srcdir)/Python/phelper.d
        dtrace -o $@ $(DFLAGS) -C -64 -h -s $(srcdir)/Python/python.d
Python/dtrace.o: $(srcdir)/Python/python.d Python/ceval.o
        dtrace -o $@ $(DFLAGS) -C -G -64 -s $(srcdir)/Python/python.d Python/ceval.o

Let’s build this bad-boy

make
make install
ln -s /a/1/languages/python244d /a/1/languages/python

Then we can take a simple dtrace script, like John Levon’s pywrites.d and see some stuff:


[jason:/tmp] root# ./pywrites.d -c ‘/a/1/languages/python244d/bin/python -V’
dtrace: script ‘./pywrites.d’ matched 2 probes
Python 2.4.4
dtrace: pid 21213 has exited
CPU ID FUNCTION:NAME 3 2 :END

libc.so.1`_write+0xa libc.so.1`_dowrite+0×54 libc.so.1`_ndoprnt+0×2cb6 libc.so.1`fprintf+0×132 libpython2.4.so.1.0`Py_Main+0×48c python`_start+0×6c 1 libc.so.1`_write+0xa libc.so.1`_ndoprnt+0×3535 libc.so.1`fprintf+0×132 libpython2.4.so.1.0`Py_Main+0×48c python`_start+0×6c 1


[jason:/tmp] root# ./pywrites.d -c “/a/1/languages/python244d/bin/django-admin.py startproject jason”
dtrace: script ‘./pywrites.d’ matched 2 probes
dtrace: pid 21812 has exited
CPU ID FUNCTION:NAME 1 2 :END

libc.so.1`_write+0xa libc.so.1`_fflush_u+0×34 libc.so.1`fclose+0×6b libpython2.4.so.1.0`file_close+0xbf libpython2.4.so.1.0`PyEval_EvalFrameReal+0×50c8 [ /a/1/languages/python244d/lib/python2.4/site-packages/django/core/management.py:803 (startproject) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalFrameReal+0×61dc [ /a/1/languages/python244d/lib/python2.4/site-packages/django/core/management.py:1599 (execute_from_command_line) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalCodeEx+0×727 libpython2.4.so.1.0`PyEval_EvalFrameReal+0×5195 [ /a/1/languages/python244d/bin/django-admin.py:5 (?) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalCodeEx+0×727 libpython2.4.so.1.0`PyEval_EvalCode+0×36 libpython2.4.so.1.0`PyRun_FileExFlags+0×97 libpython2.4.so.1.0`PyRun_SimpleFileExFlags+0×16f libpython2.4.so.1.0`Py_Main+0xac5 python`_start+0×6c 1 libc.so.1`_write+0xa libc.so.1`_fflush_u+0×34 libc.so.1`fclose+0×6b libpython2.4.so.1.0`file_close+0xbf libpython2.4.so.1.0`PyEval_EvalFrameReal+0×50c8 [ /a/1/languages/python244d/lib/python2.4/site-packages/django/core/management.py:783 (_start_helper) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalCodeEx+0×727 libpython2.4.so.1.0`PyEval_EvalFrameReal+0×5195 [ /a/1/languages/python244d/lib/python2.4/site-packages/django/core/management.py:795 (startproject) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalFrameReal+0×61dc [ /a/1/languages/python244d/lib/python2.4/site-packages/django/core/management.py:1599 (execute_from_command_line) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalCodeEx+0×727 libpython2.4.so.1.0`PyEval_EvalFrameReal+0×5195 [ /a/1/languages/python244d/bin/django-admin.py:5 (?) ] libpython2.4.so.1.0`PyEval_EvalFrame+0×1f libpython2.4.so.1.0`PyEval_EvalCodeEx+0×727 libpython2.4.so.1.0`PyEval_EvalCode+0×36 libpython2.4.so.1.0`PyRun_FileExFlags+0×97 libpython2.4.so.1.0`PyRun_SimpleFileExFlags+0×16f libpython2.4.so.1.0`Py_Main+0xac5 python`_start+0×6c 3 [jason:/tmp] root# ls jason/ init.py manage.py settings.py urls.py

I think I’m going to bring the patch up to Python 2.5 as well.

7 Comments

  1. Brett
    Posted August 29, 2007 at 1:28 pm | Permalink

    dtrace -o Python/dtrace.o -C -G -64 -s ./Python/python.d Python/ceval.o
    dtrace: failed to link script ./Python/python.d: incorrect ELF class for object file: Python/ceval.o

    —-

    $ file Python/ceval.o
    Python/ceval.o: ELF 32-bit LSB relocatable 80386 Version 1

    32-bit?

    $ which gcc
    /opt/csw/gcc4/bin/gcc

    Are you using something else?

    Double checked that I had all your changes.

  2. Posted August 29, 2007 at 2:58 pm | Permalink

    Simply awesome. I’ll definitely be needing this in short order! Thanks for the details on how to get it rolling.

  3. Posted August 29, 2007 at 4:27 pm | Permalink

    Neat. I’m curious why you need sys/socket{var}.h in
    the helper file?

    If you use gpatch -p1, you don’t need a new directory.

    You should be able to do

    make DFLAGS=”-64”

    and similarly for LDFLAGS etc to get the 64-bit build.
    It’s worth looking at the spec file:

    http://cvs.opensolaris.org/source/xref//jds/spec-files/trunk/SUNWPython.spec

    We’re upgrading to Python 2.5 in Solaris “soon”, and the patch will get updated as needed then.

  4. Posted August 29, 2007 at 8:22 pm | Permalink

    @Brett, I used gcc 3 at /usr/sfw/bin/gcc

  5. James
    Posted August 29, 2007 at 10:21 pm | Permalink

    Might I suggest adding pre { overflow: auto; } to your css.

  6. Posted August 30, 2007 at 5:28 am | Permalink

    @ john, there was some odd, and yes I know about the flags passed to makefiles. I just wanted the post to be a bit more education (at least attempted). For the sys/socket{var}.h, the build failed with some time error (I forget the exact one but can reproduce it)

    @ james, good idear, will do

  7. Posted August 30, 2007 at 5:37 am | Permalink

    @james, the pre funniness was my fault, I had a < pre ; as tag


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