First draft written

Author: maryiaLichko

doc/reference/configuration/configuration_reference.rst

@@ -3554,6 +3554,7 @@ The ``replication`` section defines configuration parameters related to :ref:`re
 -   :ref:`replication.skip_conflict <configuration_reference_replication_skip_conflict>`
 -   :ref:`replication.sync_lag <configuration_reference_replication_sync_lag>`
 -   :ref:`replication.sync_timeout <configuration_reference_replication_sync_timeout>`
+-   :ref:`replication.synchro_quorum <configuration_reference_replication_synchro_queue_max_size`
 -   :ref:`replication.synchro_quorum <configuration_reference_replication_synchro_quorum>`
 -   :ref:`replication.synchro_timeout <configuration_reference_replication_synchro_timeout>`
 -   :ref:`replication.threads <configuration_reference_replication_threads>`
@@ -4144,6 +4145,78 @@ autoexpel full example
     | Default: 0
     | Environment variable: TT_REPLICATION_SYNC_TIMEOUT
 
+
+.. _configuration_reference_replication_synchro_queue_max_size:
+
+.. confval:: replication.synchro_queue_max_size
+
+    **Since:** :doc:`3.3.0 </release/3.3.0>`
+
+    The ``replication.synchro_queue_max_size`` option controls the maximum size of the synchronous transaction queue on a master node.
+    This parameter ensures that the queue does not grow indefinitely, potentially impacting performance and resource usage.
+
+    The size is measured in bytes, with a value of 0 disabling the limit (unlimited queue, as in earlier versions).
+
+    .. NOTE::
+
+        Applies only to the master node.
+
+
+    If the synchronous queue reaches the configured size limit, new transactions attempting to enter the queue are discarded.
+    In such cases, the system returns an error to the user:
+    “The synchronous transaction queue is full.”
+
+    This size limitation does not apply during the recovery process. Transactions processed during recovery are unaffected by the queue size limit.
+
+    Use the following command to view the current size of the synchronous queue:
+
+    .. code-block:: lua
+
+        box.info.synchro.queue.size
+
+
+    .. code-block:: command line
+
+        tarantool> box.info.synchro
+        ---
+        - queue:
+            owner: 1
+            size: 60
+            busy: false
+            len: 1
+            term: 2
+            quorum: 2
+        ...
+
+    Set the synchronous queue size limit in the configuration file:
+
+    .. code-block:: yaml
+
+        replication:
+            synchro_queue_max_size: 33554432  # Limit set to 32 MB
+
+
+    .. code-block:: lua
+
+        box.cfg{
+          replication_synchro_queue_max_size = 33554432  -- Limit set to 32 MB
+        }
+
+
+    .. hint::
+
+	- Ensure the ``synchro_queue_max_size`` value is sufficient for the expected transaction workload to avoid unnecessary rejections.
+	- Setting the limit to 0 removes any restrictions but may result in unbounded queue growth.
+	- Monitor the queue size using ``box.info.synchro.queue.size`` to adjust the limit if needed.
+
+
+    |
+    | Type: integer
+    | Default: 16777216 (16 MB)
+    | Environment variable: TT_REPLICATION_SYNCHRO_QUEUE_MAX_SIZE
+
+
+
 .. _configuration_reference_replication_synchro_quorum:
 
 .. confval:: replication.synchro_quorum