--- a/testing/mozbase/mozlog/mozlog/proxy.py
+++ b/testing/mozbase/mozlog/mozlog/proxy.py
@@ -1,13 +1,16 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from .structuredlog import get_default_logger
+from multiprocessing import Queue
+from threading import Thread
+
+from .structuredlog import get_default_logger, StructuredLogger
 
 
 class ProxyLogger(object):
     """
     A ProxyLogger behaves like a
     :class:`mozlog.structuredlog.StructuredLogger`.
 
     Each method and attribute access will be forwarded to the underlying
@@ -28,8 +31,48 @@ class ProxyLogger(object):
         return getattr(self.logger, name)
 
 
 def get_proxy_logger(component=None):
     """
     Returns a :class:`ProxyLogger` for the given component.
     """
     return ProxyLogger(component)
+
+
+class QueuedProxyLogger(StructuredLogger):
+    """Logger that logs via a queue.
+
+    This is intended for multiprocessing use cases where there are
+    some subprocesses which want to share a log handler with the main thread,
+    without the overhead of having a multiprocessing lock for all logger
+    access."""
+
+    threads = {}
+
+    def __init__(self, logger):
+        StructuredLogger.__init__(self, logger.name)
+        if logger.name not in self.threads:
+            self.threads[logger.name] = LogQueueThread(Queue(), logger)
+            self.threads[logger.name].start()
+        self.queue = self.threads[logger.name].queue
+
+    def _handle_log(self, data):
+        self.queue.put(data)
+
+
+class LogQueueThread(Thread):
+    def __init__(self, queue, logger):
+        self.queue = queue
+        self.logger = logger
+        Thread.__init__(self, name="Thread-Log")
+        self.daemon = True
+
+    def run(self):
+        while True:
+            try:
+                msg = self.queue.get()
+            except (EOFError, IOError):
+                break
+            if msg is None:
+                break
+            else:
+                self.logger._handle_log(msg)

--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/environment.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/environment.py
@@ -1,17 +1,17 @@
 import json
 import os
 import multiprocessing
 import signal
 import socket
 import sys
 import time
 
-from mozlog import get_default_logger, handlers
+from mozlog import get_default_logger, handlers, proxy
 
 from wptlogging import LogLevelRewriter
 
 here = os.path.split(__file__)[0]
 
 serve = None
 sslutils = None
 
@@ -163,16 +163,18 @@ class TestEnvironment(object):
     def setup_server_logging(self):
         server_logger = get_default_logger(component="wptserve")
         assert server_logger is not None
         log_filter = handlers.LogLevelFilter(lambda x:x, "info")
         # Downgrade errors to warnings for the server
         log_filter = LogLevelRewriter(log_filter, ["error"], "warning")
         server_logger.component_filter = log_filter
 
+        server_logger = proxy.QueuedProxyLogger(server_logger)
+
         try:
             #Set as the default logger for wptserve
             serve.set_logger(server_logger)
             serve.logger = server_logger
         except Exception:
             # This happens if logging has already been set up for wptserve
             pass