Improve handling of newlines in log messages (#596)

* Avoid adding newlines to log messages

* Update CONTRIBUTORS.md

* cli: avoid skipping empty lines

* docs: update changelog

---------

Co-authored-by: Bogdan Popa <bogdan@defn.io>

CONTRIBUTORS.md

@@ -63,3 +63,4 @@ of those changes to CLEARTYPE SRL.
 | [@DiegoPomares](https://github.com/DiegoPomares/)      | Diego Pomares          |
 | [@pahrohfit](https://github.com/pahrohfit/)            | Robert Dailey          |
 | [@nhairs](https://github.com/nhairs)                   | Nicholas Hairs         |
+| [@5tefan](https://github.com/5tefan/)                  | Stefan Codrescu        |

docs/source/changelog.rst

@@ -13,10 +13,14 @@ Fixed
 
 * The ``CurrentMessage`` middleware now works under AsyncIO. (`#586`_,
   `#593`_, `@pahrohfit`_)
+* Improved logging behavior under different buffer modes. (`#596`_,
+  `@5tefan`_)
 
 .. _#586: https://github.com/Bogdanp/dramatiq/issues/586
 .. _#593: https://github.com/Bogdanp/dramatiq/pull/593
+.. _#596: https://github.com/Bogdanp/dramatiq/pull/596
 .. _@pahrohfit: https://github.com/pahrohfit
+.. _@5tefan: https://github.com/5tefan
 
 Added
 ^^^^^

dramatiq/cli.py

@@ -338,21 +338,14 @@ def watch_logs(log_filename, pipes, stop):
                 for event in events:
                     try:
                         while event.poll():
-                            # StreamHandler writes newlines into the pipe separately
-                            # from the actual log entry; to avoid back-to-back newlines
-                            # in the events pipe (causing multiple entries on a single
-                            # line), discard newline-only data from the pipe
                             try:
                                 data = event.recv_bytes()
                             except EOFError:
                                 event.close()
                                 raise
 
-                            data = data.decode("utf-8", errors="replace").rstrip("\n")
-                            if not data:
-                                continue
-
-                            log_file.write(data + "\n")
+                            data = data.decode("utf-8", errors="replace")
+                            log_file.write(data)
                             log_file.flush()
                     except BrokenPipeError:
                         event.close()