capture coordinator output

bench/client.py

@@ -124,7 +124,10 @@ def run_remote_clients(cmd: str, out: Path, err: Path, csv: Path,
     files = []
 
     # Start coordinator
-    coordinator = Coordinator(len(hosts))
+    c_out = out.parent / f'coordinator-{out.name}'
+    c_err = err.parent / f'coordinator-{err.name}'
+    coordinator = Coordinator(len(hosts), out_file=c_out, err_file=c_err)
+
     cmd += f' --coordinator {HOSTNAME}'
 
     for host in hosts:

bench/coordinator.py

@@ -12,12 +12,19 @@ COORDINATOR_EXE = f'{EMPER_CLIENT_DIR}/build/apps/coordinator'
 
 class Coordinator(subprocess.Popen):
     """Coordniator class usable in a with statement"""
-    def __init__(self, nclients):
+    def __init__(self, nclients, out_file=None, err_file=None):
+        self.fout = subprocess.DEVNULL
+        self.ferr = subprocess.DEVNULL
+        if out_file:
+            self.fout = open(out_file, 'w')
+        if err_file:
+            self.ferr = open(err_file, 'w')
+
         cmd = f'{COORDINATOR_EXE} {nclients}'
         log.debug('Creating coordinator object with cmd: %s', cmd)
         super().__init__(cmd.split(),
-                         stdout=subprocess.DEVNULL,
-                         stderr=subprocess.DEVNULL)
+                         stdout=self.fout,
+                         stderr=self.ferr)
 
     def __enter__(self):
         log.debug('Start coordinator')
@@ -26,3 +33,9 @@ class Coordinator(subprocess.Popen):
     def __exit__(self, exc_type, value, traceback):  # pylint: disable=arguments-differ
         log.debug('Join coordinator')
         super().__exit__(exc_type, value, traceback)
+
+    def __del__(self):
+        if self.fout != subprocess.DEVNULL:
+            self.fout.close()
+        if self.ferr != subprocess.DEVNULL:
+            self.ferr.close()