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+$MainMsgQueueSize
+-----------------
+
+**Type:** global configuration parameter
+
+**Default:** 50000 (v8.30.0) - may change
+
+**Description:**
+
+This allows to specify the maximum size of the message queue. This
+parameter is only available when rsyslogd has been compiled with
+multithreading support. In this mode, receiver and output modules are
+de-coupled via an in-memory queue. This queue buffers messages when the
+output modules are not capable to process them as fast as they are
+received. Once the queue size is exhausted, messages will be dropped.
+The slower the output (e.g. MySQL), the larger the queue should be.
+Buffer space for the actual queue entries is allocated on an as-needed
+basis. Please keep in mind that a very large queue may exhaust available
+system memory and swap space. Keep this in mind when configuring the max
+size. The actual size of a message depends largely on its content and
+the originator. As a rule of thumb, typically messages should not take
+up more then roughly 1k (this is the memory structure, not what you see
+in a network dump!). For typical linux messages, 512 bytes should be a
+good bet. Please also note that there is a minimal amount of memory
+taken for each queue entry, no matter if it is used or not. This is one
+pointer value, so on 32bit systems, it should typically be 4 bytes and
+on 64bit systems it should typically be 8 bytes. For example, the
+default queue size of 10,000 entries needs roughly 40k fixed overhead on
+a 32 bit system.
+
+**Sample:**
+
+``$MainMsgQueueSize 100000 # 100,000 may be a value to handle burst traffic``
+