processes.Process was raising DeadProcess for subprocesses that simply didn't emit any output.

AUTHORS

@@ -23,10 +23,11 @@ Linden Lab Contributors
 
 Thanks To
 ---------
+* Chuck Thier, reporting a bug in processes.py
 * Brantley Harris, reporting bug #4
 * Taso Du Val, reproing an exception squelching bug, saving children's lives  ;-)
 * R. Tyler Ballance, bug report on tpool on Windows, help with improving corolocal module
-* Sergey Shepelev, PEP 8 police  :-)
+* Sergey Shepelev, PEP 8 police  :-), reporting bug #5
 * Luci Stanescu, for reporting twisted hub bug
 * Marcus Cavanaugh, for test case code that has been incredibly useful in tracking down bugs
 * Brian Brunswick, for many helpful questions and suggestions on the mailing list

NEWS

@@ -13,8 +13,7 @@
 * Added support for logging x-forwarded-for header in wsgi.
 * api.tcp_server is now deprecated, will be removed in a future release.
 * Added instructions on how to generate coverage reports to the documentation.
-* Bug fixes in: wsgi.py, twistedr.py, poll.py, greenio.py, util.py, select.py
-
+* Bug fixes in: wsgi.py, twistedr.py, poll.py, greenio.py, util.py, select.py, processes.py
 
 0.9.0
 =====

eventlet/processes.py

@@ -76,6 +76,7 @@ class Process(object):
         self.send = self.child_stdin.write
         self.recv = self.child_stdout_stderr.read
         self.readline = self.child_stdout_stderr.readline
+        self._read_first_result = False
 
     def wait(self):
         return cooperative_wait(self.popen4)
@@ -94,11 +95,17 @@ class Process(object):
         raise RuntimeError("Unknown mode", mode)
 
     def read(self, amount=None):
+        """Reads from the stdout and stderr of the child process.
+        The first call to read() will return a string; subsequent
+        calls may raise a DeadProcess when EOF occurs on the pipe.
+        """
         result = self.child_stdout_stderr.read(amount)
-        if result == '':
+        if result == '' and self._read_first_result:
             # This process is dead.
             self.dead_callback()
             raise DeadProcess
+        else:
+            self._read_first_result = True
         return result
 
     def write(self, stuff):

tests/processes_test.py

@@ -25,6 +25,11 @@ class TestEchoPool(TestCase):
         finally:
             self.pool.put(proc)
     
+    def test_empty_echo(self):
+        p = processes.Process('echo', ['-n'])
+        self.assertEquals('', p.read())
+        self.assertRaises(processes.DeadProcess, p.read)
+            
 
 class TestCatPool(TestCase):
     def setUp(self):