util: Introduce NDN_LOG_NOFLUSH env variable to disable auto-flushing logs
Change-Id: Id1699d044e318aac315a545e913d0fc80306939b
Refs: #3668
diff --git a/docs/manpages/ndn-log.rst b/docs/manpages/ndn-log.rst
index b8fc3b2..40db707 100644
--- a/docs/manpages/ndn-log.rst
+++ b/docs/manpages/ndn-log.rst
@@ -18,6 +18,11 @@
setting the environment variable. Wildcards can be used to enable logging for all
modules (just ``*``) or all modules under a selected prefix (e.g., ``ndn.*``).
+If an additional environment variable ``NDN_LOG_NOFLUSH`` is set, the automatic flushing
+after each log record will be disabled. This can improve logging performance but may
+cause the log records to appear delayed or, in case of application crash, the last
+few log records may be lost.
+
ndn-cxx logging facility provides a mechanism to manage the type of log messages
that are written by classifying log messages by severity levels. Listed below
are the available log levels.