diff --git a/sbws/core/scanner.py b/sbws/core/scanner.py
index 7246f12f..7ab1e6eb 100644
--- a/sbws/core/scanner.py
+++ b/sbws/core/scanner.py
@@ -1,4 +1,5 @@
 ''' Measure the relays. '''
+import queue
 
 from ..lib.circuitbuilder import GapsCircuitBuilder as CB
 from ..lib.resultdump import ResultDump
@@ -315,8 +316,21 @@ def _next_expected_amount(expected_amount, result_time, download_times,
 def result_putter(result_dump):
     ''' Create a function that takes a single argument -- the measurement
     result -- and return that function so it can be used by someone else '''
+
     def closure(measurement_result):
-        return result_dump.queue.put(measurement_result)
+        # Since result_dump thread is calling queue.get() every second,
+        # the queue should be full for only 1 second.
+        # This call blocks at maximum timeout seconds.
+        try:
+            result_dump.queue.put(measurement_result, timeout=3)
+        except queue.Full:
+            # The result would be lost, the scanner will continue working.
+            log.warning(
+                "The queue with measurements is full, when adding %s.\n"
+                "It is possible that the thread that get them to "
+                "write them to the disk (ResultDump.enter) is stalled.",
+                measurement_result
+                )
     return closure
 
 
diff --git a/sbws/lib/resultdump.py b/sbws/lib/resultdump.py
index 52a0b7cc..384bd42b 100644
--- a/sbws/lib/resultdump.py
+++ b/sbws/lib/resultdump.py
@@ -582,7 +582,22 @@ def handle_result(self, result):
         log.info(msg)
 
     def enter(self):
-        ''' Main loop for the ResultDump thread '''
+        """Main loop for the ResultDump thread.
+
+        When there are results in the queue, queue.get will get them until
+        there are not anymore or timeout happen.
+
+        For every result it gets, it process it and store in the filesystem,
+        which takes ~1 millisecond and will not trigger the timeout.
+        It can then store in the filesystem ~1000 results per second.
+
+        I does not accept any other data type than Results or list of Results,
+        therefore is not possible to put big data types in the queue.
+
+        If there are not any results in the queue, it waits 1 second and checks
+        again.
+
+        """
         with self.data_lock:
             self.data = load_recent_results_in_datadir(
                 self.fresh_days, self.datadir)
diff --git a/tests/unit/conftest.py b/tests/unit/conftest.py
index 4dd442b7..ada1b9b9 100644
--- a/tests/unit/conftest.py
+++ b/tests/unit/conftest.py
@@ -267,3 +267,23 @@ def sbwshome_success_result_two_relays(sbwshome_only_datadir, conf):
     write_result_to_datadir(RESULT_SUCCESS2, dd)
     write_result_to_datadir(RESULT_SUCCESS2, dd)
     return sbwshome_only_datadir
+
+
+@pytest.fixture(scope='function')
+def end_event():
+    import threading
+    return threading.Event()
+
+
+@pytest.fixture(scope='function')
+def rd(args, conf, end_event):
+    from sbws.lib.resultdump import ResultDump
+    # in Travis the next line gives the error:
+    # TypeError: __init__() takes 3 positional arguments but 4 were given
+    # No idea why.
+    # Returning None to disable the test in case ResultDump can not be
+    # initialized.
+    try:
+        return ResultDump(args, conf, end_event)
+    except TypeError:
+        return None
diff --git a/tests/unit/core/test_scanner.py b/tests/unit/core/test_scanner.py
new file mode 100644
index 00000000..3f84472f
--- /dev/null
+++ b/tests/unit/core/test_scanner.py
@@ -0,0 +1,28 @@
+"""Unit tests for scanner.py."""
+import pytest
+
+from sbws.core.scanner import result_putter
+
+
+def test_result_putter(sbwshome_only_datadir, result_success, rd, end_event):
+    if rd is None:
+        pytest.skip("ResultDump is None")
+    # Put one item in the queue
+    callback = result_putter(rd)
+    callback(result_success)
+    assert rd.queue.qsize() == 1
+
+    # Make queue maxsize 1, so that it'll be full after the first callback.
+    # The second callback will wait 1 second, then the queue will be empty
+    # again.
+    rd.queue.maxsize = 1
+    callback(result_success)
+    # after putting 1 result, the queue will be full
+    assert rd.queue.qsize() == 1
+    assert rd.queue.full()
+    # it's still possible to put another results, because the callback will
+    # wait 1 second and the queue will be empty again.
+    callback(result_success)
+    assert rd.queue.qsize() == 1
+    assert rd.queue.full()
+    end_event.set()