fixes to pyabc kill mechanism

src/python/module.make

@@ -61,4 +61,21 @@ pyabc.tgz : $(PROG) $(ABC_PYTHON_SRC:_wrap.c=.py) $(ABC_PYTHON_FILES_PREFIX)/abc
         --out=$@ \
         $(ABC_PYTHON_OPTIONS)
 
+PYABC_INSTALL_TARGET ?= $(shell date +%Y-%m-%d_%H-%M.%N_${USER})
+PYABC_INSTALL_TARGET := $(PYABC_INSTALL_TARGET)
+
+PYABC_INSTALL_DIR ?= /hd/common/pyabc/builds/pyabc_builds/
+
+.PHONY: zzz
+
+pyabc_install_target: pyabc_extension_bdist
+    mkdir -p "$(PYABC_INSTALL_DIR)/$(PYABC_INSTALL_TARGET)"
+    tar \
+       --directory="$(PYABC_INSTALL_DIR)/$(PYABC_INSTALL_TARGET)" \
+       --show-transformed-names \
+       --transform='s#^.*/##g' \
+       -xvzf "$(ABC_PYTHON_FILES_PREFIX)/dist/pyabc-1.0.linux-x86_64.tar.gz"
+    find "$(PYABC_INSTALL_DIR)/$(PYABC_INSTALL_TARGET)/"* -type d | xargs rmdir
+    echo "Installed at $(PYABC_INSTALL_DIR)/$(PYABC_INSTALL_TARGET)"       
+
 endif

src/python/pyabc.i

@@ -23,9 +23,18 @@
 %{
     
 #include <main.h>
+#include <utilCex.h>
+
 #include <stdlib.h>
 #include <signal.h>
-#include "utilSignal.h"
+
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
     
 int n_ands()
 {
@@ -160,6 +169,56 @@ int n_phases()
     return pNtk ? Abc_NtkPhaseFrameNum(pNtk) : 1;
 }
 
+Abc_Cex_t* _cex_get()
+{
+    Abc_Frame_t* pAbc = Abc_FrameGetGlobalFrame();
+    Abc_Cex_t* pCex = Abc_FrameReadCex(pAbc);
+    
+    if ( ! pCex )
+    {
+        return NULL;
+    }
+
+    return Abc_CexDup( pCex, -1 ); 
+}
+
+void _cex_put(Abc_Cex_t* pCex)
+{
+    Abc_Frame_t* pAbc = Abc_FrameGetGlobalFrame();
+    
+    if ( pCex )
+    {
+        pCex = Abc_CexDup(pCex, -1);
+    }
+    
+    Abc_FrameSetCex( Abc_CexDup(pCex, -1) );
+}
+
+void _cex_free(Abc_Cex_t* pCex)
+{
+    Abc_CexFree(pCex);
+}
+
+int _cex_n_regs(Abc_Cex_t* pCex)
+{
+    return pCex->nRegs;
+}
+
+int _cex_n_pis(Abc_Cex_t* pCex)
+{
+    return pCex->nPis;
+}
+
+int _cex_get_po(Abc_Cex_t* pCex)
+{
+    return pCex->iPo;
+}
+
+int _cex_get_frame(Abc_Cex_t* pCex)
+{
+    return pCex->iFrame;
+}
+
 static PyObject* pyabc_internal_python_command_callback = 0;
 
 void pyabc_internal_set_command_callback( PyObject* callback )
@@ -170,6 +229,8 @@ void pyabc_internal_set_command_callback( PyObject* callback )
     pyabc_internal_python_command_callback = callback;
 }
 
+PyThreadState *_save;
+
 static int pyabc_internal_abc_command_callback(Abc_Frame_t * pAbc, int argc, char ** argv)
 {
     int i;
@@ -183,6 +244,8 @@ static int pyabc_internal_abc_command_callback(Abc_Frame_t * pAbc, int argc, cha
     if ( !pyabc_internal_python_command_callback )
             return 0;
             
+    Py_BLOCK_THREADS
+            
     args = PyList_New(argc);
     
     for( i=0 ; i<argc ; i++ )
@@ -196,19 +259,30 @@ static int pyabc_internal_abc_command_callback(Abc_Frame_t * pAbc, int argc, cha
 
     if ( !res )
     {
+        Py_UNBLOCK_THREADS
         return -1;
     }
     
     lres = PyInt_AsLong(res);
     Py_DECREF(res);
 
+    Py_UNBLOCK_THREADS
+    
     return lres;
 }
 
 int run_command(char* cmd)
 {
     Abc_Frame_t* pAbc = Abc_FrameGetGlobalFrame();
-    return Cmd_CommandExecute(pAbc, cmd);
+    int rc;
+    
+    Py_UNBLOCK_THREADS
+    
+    rc = Cmd_CommandExecute(pAbc, cmd);
+    
+    Py_BLOCK_THREADS
+    
+    return rc;
 }
 
 void pyabc_internal_register_command( char * sGroup, char * sName, int fChanges )
@@ -218,45 +292,212 @@ void pyabc_internal_register_command( char * sGroup, char * sName, int fChanges
     Cmd_CommandAdd( pAbc, sGroup, sName, (void*)pyabc_internal_abc_command_callback, fChanges);
 }
 
+static int sigchld_pipe_fd = -1;
+    
+static void sigchld_handler(int signum)
+{
+    while( write(sigchld_pipe_fd, "", 1) == -1 && errno==EINTR )
+        ;
+}
+
+static void install_sigchld_handler(int sigchld_fd)
+{
+    sigchld_pipe_fd = sigchld_fd;
+    signal(SIGCHLD, sigchld_handler);
+}
+
+static int sigint_pipe_fd = -1;
+
 static void sigint_handler(int signum)
 {
-    Util_SignalCleanup();
-    _exit(1);
+    unsigned char tmp = (unsigned char)signum;
+    while( write(sigint_pipe_fd, &tmp, 1) == -1 && errno==EINTR )
+        ;
 }
 
-void add_child_pid(int pid)
+static void install_sigint_handler(int sigint_fd)
 {
-    Util_SignalAddChildPid(pid);
+    sigint_pipe_fd = sigint_fd;
+    
+    signal(SIGINT, sigint_handler);
+
+    // try to catch other signals that ask the process to terminate    
+    signal(SIGABRT, sigint_handler);
+    signal(SIGQUIT, sigint_handler);
+    signal(SIGTERM, sigint_handler);
+
+    // try to ensure cleanup on exceptional conditions
+    signal(SIGBUS, sigint_handler);
+    signal(SIGILL, sigint_handler);
+    signal(SIGSEGV, sigint_handler);
+    
+    // try to ensure cleanup before being killed due to resource limit
+    signal(SIGXCPU, sigint_handler);
+    signal(SIGXFSZ, sigint_handler);
 }
 
-void remove_child_pid(int pid)
-{
-    Util_SignalRemoveChildPid(pid);
-}
+sigset_t old_procmask;
+static int nblocks = 0;
 
 void block_sigint()
 {
-    Util_SignalBlockSignals();
+    sigset_t procmask;
+
+    assert(nblocks==0);
+    nblocks ++ ;
+    
+    sigemptyset(&procmask);
+    sigaddset(&procmask, SIGINT);
+    
+    sigprocmask(SIG_BLOCK, &procmask, &old_procmask);
 }
 
-void restore_sigint_block()
+void unblock_sigint()
 {
-    Util_SignalUnblockSignals();
+    assert( nblocks==1);
+    nblocks--;
+    
+    sigprocmask(SIG_SETMASK, &old_procmask, NULL);
 }
 
-void reset_sigint_handler()
+static PyObject* pyabc_internal_system_callback = 0;
+static PyObject* pyabc_internal_tmpfile_callback = 0;
+static PyObject* pyabc_internal_tmpfile_remove_callback = 0;
+
+int Util_SignalSystem(const char* cmd)
 {
-    Util_SignalResetHandler();
+    PyObject* arglist;
+    PyObject* res;
+
+    long lres;
+    
+    if ( !pyabc_internal_system_callback )
+            return -1;
+            
+    Py_BLOCK_THREADS
+            
+    arglist = Py_BuildValue("(O)", PyString_FromString(cmd));
+    Py_INCREF(arglist);
+
+    res = PyEval_CallObject( pyabc_internal_system_callback, arglist );
+    Py_DECREF(arglist);
+
+    if ( !res )
+    {
+        Py_UNBLOCK_THREADS
+        return -1;
+    }
+    
+    lres = PyInt_AsLong(res);
+    Py_DECREF(res);
+
+    Py_UNBLOCK_THREADS
+    
+    return lres;
 }
 
+int Util_SignalTmpFile(const char* prefix, const char* suffix, char** out_name)
+{
+    char* str;
+    Py_ssize_t size;
+    
+    PyObject* arglist;
+    PyObject* res;
+    
+    *out_name = NULL;
+
+    if ( !pyabc_internal_tmpfile_callback )
+            return 0;
+            
+    Py_BLOCK_THREADS
+            
+    arglist = Py_BuildValue("(ss)", prefix, suffix);
+    Py_INCREF(arglist);
+
+    res = PyEval_CallObject( pyabc_internal_tmpfile_callback, arglist );
+    Py_DECREF(arglist);
+
+    if ( !res )
+    {
+        Py_UNBLOCK_THREADS
+        return -1;
+    }
+    
+    PyString_AsStringAndSize(res, &str, &size);
+    
+    *out_name = ABC_ALLOC(char, size+1);
+    strcpy(*out_name, str);
+    
+    Py_DECREF(res);
+
+    Py_UNBLOCK_THREADS
+    
+    return open(*out_name, O_WRONLY);
+}
+
+void Util_SignalTmpFileRemove(const char* fname, int fLeave)
+{
+    PyObject* arglist;
+    PyObject* res;
+
+    if ( !pyabc_internal_tmpfile_remove_callback )
+            return;
+            
+    Py_BLOCK_THREADS
+            
+    arglist = Py_BuildValue("(si)", fname, fLeave);
+    Py_INCREF(arglist);
+
+    res = PyEval_CallObject( pyabc_internal_tmpfile_remove_callback, arglist );
+    Py_DECREF(arglist);
+    Py_XDECREF(res);
+
+    Py_UNBLOCK_THREADS
+}
+
+void pyabc_internal_set_util_callbacks( PyObject* system_callback, PyObject* tmpfile_callback, PyObject* tmpfile_remove_callback )
+{
+    Py_XINCREF(system_callback);
+    Py_XDECREF(pyabc_internal_system_callback);
+
+    pyabc_internal_system_callback = system_callback;
+
+    Py_XINCREF(tmpfile_callback);
+    Py_XDECREF(pyabc_internal_tmpfile_callback);
+
+    pyabc_internal_tmpfile_callback = tmpfile_callback;
+
+    Py_XINCREF(tmpfile_remove_callback);
+    Py_XDECREF(pyabc_internal_tmpfile_remove_callback);
+
+    pyabc_internal_tmpfile_remove_callback = tmpfile_remove_callback;
+}
+
+PyObject* _wait_no_hang()
+{
+    int status;
+    int pid;
+    
+    pid = wait3(&status, WNOHANG, NULL);
+    
+    return Py_BuildValue("(iii)", pid, status, errno);
+}
+
+int _posix_kill(int pid, int signum)
+{
+    return kill(pid, signum);
+}
+
+void _set_death_signal()
+{
+    prctl(PR_SET_PDEATHSIG, SIGINT);
+}
 
 %}
 
 %init 
 %{
     Abc_Start();
-    Util_SignalStartHandler();
-    signal(SIGINT, sigint_handler);
 %}
 
 int n_ands();
@@ -281,18 +522,442 @@ int  cex_frame();
 
 int  n_phases();
 
+Abc_Cex_t* _cex_get();
+void _cex_put(Abc_Cex_t* pCex);
+void _cex_free(Abc_Cex_t* pCex);
+int _cex_n_regs(Abc_Cex_t* pCex);
+int _cex_n_pis(Abc_Cex_t* pCex);
+int _cex_get_po(Abc_Cex_t* pCex);
+int _cex_get_frame(Abc_Cex_t* pCex);
+
 void pyabc_internal_set_command_callback( PyObject* callback );
 void pyabc_internal_register_command( char * sGroup, char * sName, int fChanges );
 
+void install_sigchld_handler(int sigint_fd);
+void install_sigint_handler(int sigint_fd);
+
 void block_sigint();
-void restore_sigint_block();
-void add_child_pid(int pid);
-void remove_child_pid(int pid);
-void reset_sigint_handler();
+void unblock_sigint();
+
+void pyabc_internal_set_util_callbacks( PyObject* system_callback, PyObject* tmpfile_callback, PyObject* tmpfile_remove_callback );
+
+PyObject* _wait_no_hang();
+
+void _set_death_signal();
+
+int _posix_kill(int pid, int signum);
+void _set_death_signal();
 
 %pythoncode 
 %{
 
+class _Cex(object):
+
+    def __init__(self, pCex):
+        self.pCex = pCex
+        
+    def __del__(self):
+        _cex_free(self.pCex)
+
+    def n_regs(self):
+        return _cex_n_regs(self.pCex)
+        
+    def n_pis(self):
+        return _cex_n_pis(self.pCex)
+    
+    def get_po(self):
+        return _cex_get_po(self.pCex)
+
+    def get_frame(self):
+        return _cex_get_frame(self.pCex)
+       
+def cex_get():
+
+    cex = _cex_get()
+    
+    if cex is None:
+        return None
+        
+    return _Cex(_cex_get())
+
+def cex_put(cex):
+
+    assert cex is not None
+    assert cex.pCex is not None
+    
+    return _cex_put(cex.pCex)
+        
+import threading
+import select
+import signal
+import tempfile
+import os
+import errno
+import sys, traceback
+import subprocess
+
+_active_lock = threading.Lock()
+_die_flag = False
+
+_active_pids = set()
+_active_temp_files = set()
+
+_terminated_pids_cond = threading.Condition(_active_lock)
+_terminated_pids = {}
+
+def add_temp_file(fname):
+    with _active_lock:
+        _active_temp_files.add(fname)
+            
+def remove_temp_file(fname):
+    with _active_lock:
+        _active_temp_files.remove(fname)
+            
+_old_os_wait3 = os.wait3
+_select_select = select.select
+
+def _retry_select(fd):
+    while True:
+        try:
+            rrdy,_,_ = _select_select([fd],[],[])
+            if fd in rrdy:
+                return
+        except select.error as e:
+            if e[0] == errno.EINTR:
+                continue
+            raise
+
+def _retry_read(fd):
+
+    while True:
+        try:
+            return fd.read(1)
+        except OSError as e:
+            if e.errno == errno.EINTR:
+                continue
+            raise
+
+def _retry_wait():
+
+    while True:
+        
+        pid, status, e = _wait_no_hang()
+        
+        if pid>0:
+            return pid, status
+            
+        elif pid==0:
+            return 0,0
+            
+        elif pid == -1 and e == errno.ECHILD:
+            return 0,0
+            
+        elif pid==-1 and e != errno.EINTR:
+            raise OSError(e, 'unknown error in wait3()')
+
+def _sigint_wait_thread_func(fd):
+
+    global _die_flag
+    
+    while True:
+        
+        _retry_select(fd)
+        _retry_read(fd) 
+
+        with _active_lock:
+        
+            if _die_flag:
+                os._exit(-1)
+            
+            _die_flag = True
+        
+            for pid in _active_pids:
+                rc = _posix_kill(pid, signal.SIGINT)
+    
+            for fname in _active_temp_files:
+                os.remove(fname)
+
+            os._exit(-1)
+
+def _child_wait_thread_func(fd):
+
+    while True:
+    
+        _retry_select(fd)
+        rc = _retry_read(fd)
+                
+        with _active_lock:
+        
+            while True:
+            
+                pid, status = _retry_wait()
+
+                if pid==0:
+                    break
+                    
+                if pid in _active_pids:
+                    _active_pids.remove(pid)
+                    
+                _terminated_pids[pid] = status
+                _terminated_pids_cond.notifyAll()
+
+_sigint_pipe_read_fd = -1
+_sigint_pipe_write_fd = -1
+
+_sigchld_pipe_read_fd = -1
+_sigchld_pipe_write_fd = -1
+
+def _start_threads():
+
+    global _sigint_pipe_read_fd, _sigint_pipe_write_fd
+    
+    _sigint_pipe_read_fd, _sigint_pipe_write_fd = os.pipe()
+    sigint_read = os.fdopen(_sigint_pipe_read_fd, "r", 0 )
+    
+    sigint_wait_thread = threading.Thread(target=_sigint_wait_thread_func, name="SIGINT wait thread", args=(sigint_read,))
+    sigint_wait_thread.setDaemon(True)
+    sigint_wait_thread.start()
+    
+    install_sigint_handler(_sigint_pipe_write_fd)
+    
+    global _sigchld_pipe_read_fd, _sigchld_pipe_write_fd
+  
+    _sigchld_pipe_read_fd, _sigchld_pipe_write_fd = os.pipe()
+    sigchld_read = os.fdopen(_sigchld_pipe_read_fd, "r", 0 )
+    
+    child_wait_thread = threading.Thread(target=_child_wait_thread_func, name="child process wait thread", args=(sigchld_read,))
+    child_wait_thread.setDaemon(True)
+    child_wait_thread.start()
+    
+    install_sigchld_handler(_sigchld_pipe_write_fd)
+
+_close_on_fork = []
+
+def close_on_fork(fd):
+    _close_on_fork.append(fd)
+
+def after_fork():
+
+    _set_death_signal()
+
+    global _close_on_fork
+
+    for fd in _close_on_fork:
+        os.close(fd)
+        
+    _close_on_fork = []
+
+    os.close(_sigint_pipe_read_fd)
+    os.close(_sigint_pipe_write_fd)
+    
+    os.close(_sigchld_pipe_read_fd)
+    os.close(_sigchld_pipe_write_fd)
+   
+    global _active_lock
+    _active_lock = threading.Lock()
+
+    global _terminated_pids_cond
+    _terminated_pids_cond = threading.Condition(_active_lock)
+    
+    global _terminated_pids
+    _terminated_pids = {}
+    
+    global _active_pids
+    _active_pids = set()
+    
+    global _active_temp_files
+    _active_temp_files = set()
+    
+    _start_threads()
+
+class _sigint_block_section(object):
+    def __init__(self):
+        self.blocked = False
+        
+    def __enter__(self):
+        block_sigint()
+        self.blocked = True
+        
+    def __exit__(self, type, value, traceback):
+        self.release()
+        
+    def release(self):
+        if self.blocked:
+            self.blocked = False
+            unblock_sigint()
+
+_old_os_fork = os.fork
+
+def _fork():
+
+    ppid = os.getpid()
+
+    with _sigint_block_section() as cs:
+    
+        with _active_lock:
+        
+            if _die_flag:
+                os._exit(-1)
+    
+            pid = _old_os_fork()
+    
+            if pid == 0:
+                after_fork()
+            
+            if pid > 0:
+                _active_pids.add(pid)  
+    
+            return pid
+    
+def _waitpid(pid, options=0):
+    
+    while True:
+    
+        with _active_lock:
+        
+            if pid in _terminated_pids:
+                status = _terminated_pids[pid]
+                del _terminated_pids[pid]
+                return pid, status
+            
+            if options==os.WNOHANG:
+                return 0, 0
+                
+            _terminated_pids_cond.wait()
+
+def _wait(options=0):
+
+    while True:
+        
+        with _active_lock:
+        
+            for pid, status in _terminated_pids.iteritems():
+                del _terminated_pids[pid]
+                return pid, status
+            
+            if options==os.WNOHANG:
+                return 0, 0
+                
+            _terminated_pids_cond.wait()
+
+_old_os_kill = os.kill
+
+def _kill(pid, sig):
+
+    with _active_lock:
+    
+        if pid in _terminated_pids:
+            return None
+            
+        return _old_os_kill(pid,sig)
+    
+os.kill = _kill
+os.fork = _fork
+os.wait = _wait
+os.waitpid = _waitpid
+
+def _split_command_line(cmd):
+    
+    args = []
+    
+    i=0
+    
+    while i<len(cmd):
+        
+        while i<len(cmd) and cmd[i] in [' ','\t','\f']:
+            i += 1
+            
+        if i >= len(cmd):
+            break
+            
+        arg = []
+        
+        in_quotes = None
+
+        while i<len(cmd):
+            
+            if not in_quotes and cmd[i] in ['\'','\"','\'']:
+                in_quotes = cmd[i]
+                
+            elif in_quotes and cmd[i]==in_quotes:
+                in_quotes = None
+                
+            elif cmd[i] == '\\' and i<(len(cmd)+1):
+                
+                i += 1
+                
+                if cmd[i]=='\\':
+                    arg.append('\\')
+                elif cmd[i]=='\'':
+                    arg.append('\'')
+                elif cmd[i]=='\"':
+                    arg.append('\'')
+                elif cmd[i]=='\"':
+                    arg.append('\"')
+                elif cmd[i]=='a':
+                    arg.append('\a')
+                elif cmd[i]=='b':
+                    arg.append('\b')
+                elif cmd[i]=='n':
+                    arg.append('\n')
+                elif cmd[i]=='f':
+                    arg.append('\f')
+                elif cmd[i]=='r':
+                    arg.append('\r')
+                elif cmd[i]=='t':
+                    arg.append('\t')
+                elif cmd[i]=='v':
+                    arg.append('\v')
+                else:
+                    arg.append(cmd[i])
+                    
+            elif not in_quotes and cmd[i] in [' ','\t','\f']:
+                break
+                
+            else:
+                arg.append(cmd[i])
+                
+            i += 1
+        
+        args.append( "".join(arg) )
+    
+    return args
+
+
+def system(cmd):
+
+    args = _split_command_line(cmd)
+    
+    if args[-2] == '>':
+    
+        with open(args[-1],'w') as fout:
+            p = subprocess.Popen(args[:-2], stdout=fout)
+            rc = p.wait()
+            return rc
+         
+    else:
+        p = subprocess.Popen(args)
+        return p.wait()
+
+def tmpfile(prefix, suffix):
+
+    with _active_lock:
+        with tempfile.NamedTemporaryFile(delete=False, prefix=prefix, suffix=suffix) as file:
+            _active_temp_files.add(file.name)
+            return file.name
+       
+def tmpfile_remove(fname, leave):
+
+    with _active_lock:
+        os.remove(fname)
+        _active_temp_files.remove(fname) 
+
+pyabc_internal_set_util_callbacks( system, tmpfile,tmpfile_remove )
+
+
+_start_threads()
+
+
 _registered_commands = {}
 
 def _cmd_callback(args):
@@ -309,7 +974,8 @@ def _cmd_callback(args):
         return res
     
     except Exception, e:
-        print "Python error: ", e
+        import traceback
+        traceback.print_exc()
 
     except SystemExit, se:
         pass
@@ -322,14 +988,11 @@ def add_abc_command(fcmd, group, cmd, change):
     _registered_commands[ cmd ] = fcmd
     pyabc_internal_register_command( group, cmd, change)
 
-import sys
 import optparse
-import os.path
 
-import __main__
+xxx = {} 
 
 def cmd_python(cmd_args):
-    global __main__
     
     usage = "usage: %prog [options] <Python files>"
     
@@ -345,7 +1008,7 @@ def cmd_python(cmd_args):
         return 0
     
     if options.cmd:
-        exec options.cmd in __main__.__dict__
+        exec options.cmd in xxx
         return 0
     
     scripts_dir = os.getenv('ABC_PYTHON_SCRIPTS', ".")
@@ -353,12 +1016,12 @@ def cmd_python(cmd_args):
     
     for fname in args[1:]:
         if os.path.isabs(fname):
-            execfile(fname, __main__.__dict__)
+            execfile(fname, xxx)
         else:
             for d in scripts_dirs:
                 fname = os.path.join(scripts_dir, fname)
                 if os.path.exists(fname):
-                    execfile(fname, __main__.__dict__)
+                    execfile(fname, xxx)
                     break
     
     return 0

src/python/pyabc_split.py

@@ -15,7 +15,6 @@ Caveats:
 
 1. Global variables in the parent process are not affected by the child processes.
 2. The functions can only return simple types, see the pickle module for details
-3. Signals are currently not handled correctly
 
 Usage:
 
@@ -91,47 +90,6 @@ from contextlib import contextmanager
 
 import pyabc
 
-def _waitpid(pid, flags):
-    while True:
-        try:
-            res =  os.waitpid(pid, flags)
-            return res
-        except OSError as e:
-            if e.errno != errno.EINTR:
-                raise
-
-def _wait():
-    while True:
-        try:
-            pid,rc = os.wait()
-            return pid, rc
-        except OSError as e:
-            if e.errno != errno.EINTR:
-                raise
-        except Exceptions as e:
-            raise
-
-class _sigint_critical_section(object):
-    def __init__(self):
-        self.blocked = False
-        
-    def __enter__(self):
-        self.acquire()
-        return self
-        
-    def __exit__(self, type, value, traceback):
-        self.release()
-        
-    def acquire(self):
-        if not self.blocked:
-            self.blocked = True
-            pyabc.block_sigint()
-
-    def release(self):
-        if self.blocked:
-            self.blocked = False
-            pyabc.restore_sigint_block()
-
 class _splitter(object):
     
     def __init__(self, funcs):
@@ -144,18 +102,19 @@ class _splitter(object):
         return len(self.fds) == 0
     
     def cleanup(self):
-        
         # close pipes and kill child processes
         for pid,(i,fd) in self.fds.iteritems():
             os.close(fd)
-            os.kill( pid, signal.SIGINT )
+            try:
+                os.kill( pid, signal.SIGINT )
+            except Exception as e:
+                print >>sys.stderr, 'exception while trying to kill pid=%d: '%pid, e
+                raise
         
-        with _sigint_critical_section() as cs:
             # wait for termination and update result
-            for pid, _ in self.fds.iteritems():
-                _waitpid( pid, 0 )
-                pyabc.remove_child_pid(pid)
-                self.results[pid] = None
+        for pid, _ in self.fds.iteritems():
+            os.waitpid( pid, 0 )
+            self.results[pid] = None
             
         self.fds = {}
 
@@ -179,22 +138,20 @@ class _splitter(object):
         
         try:
 
-            with _sigint_critical_section() as cs:
-                # create child process
-                pid = os.fork()
-        
-                if pid == 0:
-                    # child process:
-                    pyabc.reset_sigint_handler()
-                    cs.release()
-                    os.close(pr)
-                    rc = self.child( pw, f)
-                    os._exit(rc)
-                else:
-                    # parent process:
-                    pyabc.add_child_pid(pid)
-                    os.close(pw)
-                    return (pid, pr)
+            # create child process
+            pid = os.fork()
+    
+            if pid == 0:
+                # child process:
+                os.close(pr)
+                pyabc.close_on_fork(pw)
+                
+                rc = self.child( pw, f)
+                os._exit(rc)
+            else:
+                # parent process:
+                os.close(pw)
+                return (pid, pr)
                 
         finally:
             if os.getpid() != parentpid:
@@ -209,12 +166,9 @@ class _splitter(object):
     def get_next_result(self):
     
         # wait for the next child process to terminate
-        pid, rc = _wait()
+        pid, rc = os.wait()
         assert pid in self.fds
         
-        with _sigint_critical_section() as cs:
-            pyabc.remove_child_pid(pid)
-        
         # retrieve the pipe file descriptor1
         i, fd = self.fds[pid]
         del self.fds[pid]