improved explanation of "max_fsm_queue" option; included this option in ejabberd.cfg.example (EJAB-1185)

1 files changed, 18 insertions, 2 deletions

diff --git a/doc/guide.tex b/doc/guide.tex
index f8c00fdd1..c3657c9ae 100644
--- a/doc/guide.tex
+++ b/doc/guide.tex
@@ -881,7 +881,15 @@ This is a detailed description of each option allowed by the listening modules:
     The option can be defined in \term{ejabberd.cfg}, expressing the time
     in seconds: \verb|{http_poll_timeout, 300}.|
   \titem{\{max\_fsm\_queue, Size\}}
-    This option specifies the maximum number of elements in the queue of the FSM.
+    This option specifies the maximum number of elements in the queue of the FSM
+    (Finite State Machine).
+    Roughly speaking, each message in such queues represents one XML
+    stanza queued to be sent into its relevant outgoing stream. If queue size
+    reaches the limit (because, for example, the receiver of stanzas is too slow),
+    the FSM and the corresponding connection (if any) will be terminated
+    and error message will be logged.
+    The reasonable value for this option depends on your hardware configuration.
+    However, there is no much sense to set the size above 1000 elements.
     This option can be specified for \term{ejabberd\_service} and
     \term{ejabberd\_c2s} listeners,
     or also globally for \term{ejabberd\_s2s\_out}.
@@ -969,7 +977,15 @@ There are some additional global options that can be specified in the ejabberd c
   The maximum allowed delay for retry to connect after a failed connection attempt.
   Specified in seconds. The default value is 300 seconds (5 minutes).
   \titem{\{max\_fsm\_queue, Size\}}
-    This option specifies the maximum number of elements in the queue of the FSM.
+    This option specifies the maximum number of elements in the queue of the FSM
+    (Finite State Machine).
+    Roughly speaking, each message in such queues represents one XML
+    stanza queued to be sent into its relevant outgoing stream. If queue size
+    reaches the limit (because, for example, the receiver of stanzas is too slow),
+    the FSM and the corresponding connection (if any) will be terminated
+    and error message will be logged.
+    The reasonable value for this option depends on your hardware configuration.
+    However, there is no much sense to set the size above 1000 elements.
     This option can be specified for \term{ejabberd\_service} and
     \term{ejabberd\_c2s} listeners,
     or also globally for \term{ejabberd\_s2s\_out}.