diff --git a/swh/indexer/producer.py b/swh/indexer/producer.py
index 1c9d02a..a3a78ed 100755
--- a/swh/indexer/producer.py
+++ b/swh/indexer/producer.py
@@ -1,85 +1,103 @@
 # Copyright (C) 2016-2017  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import click
 import random
 import sys
 
 from swh.core import utils
 from swh.model import hashutil
 from swh.scheduler.utils import get_task
 
 
 def read_from_stdin():
     for sha1 in sys.stdin:
         yield hashutil.hash_to_bytes(sha1.strip())
 
 
 def gen_sha1(batch, dict_with_key=None):
     """Generate batch of grouped sha1s from the objstorage.
 
     """
     def _gen():
         for sha1s in utils.grouper(read_from_stdin(), batch):
             sha1s = list(sha1s)
             random.shuffle(sha1s)
             yield sha1s
 
     if dict_with_key:
         for sha1s in _gen():
             yield [{dict_with_key: sha1} for sha1 in sha1s]
     else:
         yield from _gen()
 
 
-def run_with_limit(task, limit, batch, dict_with_key=None):
+def make_function_execute(task, sync):
+    """Compute a function which executes computations on sha1s
+       synchronously or asynchronously.
+
+    """
+    if sync:
+        return (lambda sha1s, task=task: task(sha1s))
+    return (lambda sha1s, task=task: task.delay(sha1s))
+
+
+def run_with_limit(task, limit, batch, dict_with_key=None, sync=False):
+    execute_fn = make_function_execute(task, sync)
+
     count = 0
     for sha1s in gen_sha1(batch, dict_with_key):
         count += len(sha1s)
-        task.delay(sha1s)
+        execute_fn(sha1s)
         print('%s sent - [%s, ...]' % (len(sha1s), sha1s[0]))
         if count >= limit:
             return
 
 
-def run(task, batch, dict_with_key=None):
+def run(task, batch, dict_with_key=None, sync=False):
+    execute_fn = make_function_execute(task, sync)
+
     for sha1s in gen_sha1(batch, dict_with_key):
-        task.delay(sha1s)
+        execute_fn(sha1s)
         print('%s sent - [%s, ...]' % (len(sha1s), sha1s[0]))
 
 
 @click.command(help='Read sha1 from stdin and send them for indexing')
 @click.option('--limit', default=None, help='Limit the number of data to read')
 @click.option('--batch', default='10', help='Group data by batch')
-@click.option('--task-name', default='orchestrator_all', help='')
+@click.option('--task-name', default='orchestrator_all', help='Task\'s name')
+@click.option('--sync/--nosync', default=False,
+              help='Make the producer actually execute the routine.')
 @click.option('--dict-with-key', default=None)
-def main(limit, batch, task_name, dict_with_key):
+def main(limit, batch, task_name, sync, dict_with_key):
     """Read sha1 from stdin and send them for indexing.
 
     By default, send directly list of hashes.  Using the
     --dict-with-key, this will send dict list with one key mentioned
     as parameter to the dict-with-key flag.
 
     """
     batch = int(batch)
 
     from . import tasks, TASK_NAMES  # noqa
     possible_tasks = TASK_NAMES.keys()
 
     if task_name not in possible_tasks:
         print('The task_name can only be one of %s' %
               ', '.join(possible_tasks))
         return
 
     task = get_task(TASK_NAMES[task_name])
 
     if limit:
-        run_with_limit(task, int(limit), batch, dict_with_key)
+        run_with_limit(task, int(limit), batch,
+                       dict_with_key=dict_with_key, sync=sync)
     else:
-        run(task, batch, dict_with_key)
+        run(task, batch,
+            dict_with_key=dict_with_key, sync=sync)
 
 
 if __name__ == '__main__':
     main()