op-guide: add description for txn-local-latches

op-guide/tidb-config-file.md

@@ -222,3 +222,17 @@ The Plan Cache configuration of the `prepare` statement.
 - The maximum timeout time when executing a transaction commit
 - Default: 41s
 - It is required to set this value larger than twice of the Raft election timeout time
+
+### txn-local-latches
+
+Configuration about the transaction latch. It is recommended to enable it when many local transaction conflicts occur.
+
+### `enable`
+
+- To enable
+- Default: false
+
+### `capacity`
+
+- The number of slots corresponding to Hash, which automatically adjusts upward to an exponential multiple of 2. Each slot occupies 32 Bytes of memory. If set too small, it may result in slower running speed and poor performance under the scenario where the range of written data is relatively wide (such as the imported data).
+- Default: 1024000 

tools/tidb-binlog-kafka.md

@@ -93,6 +93,20 @@ cd tidb-binlog-latest-linux-amd64
     dir = "/path/pb-dir"
     ```
 
+- The drainer outputs `kafka` and you need to set the following parameters in the configuration file:
+
+    ```
+    [syncer]
+    db-type = "kafka"
+
+    # when db-type is kafka, you can uncomment this to config the down stream kafka, or it will be the same kafka addrs where drainer pull binlog from.
+    # [syncer.to]
+    # kafka-addrs = "127.0.0.1:9092"
+    # kafka-version = "0.8.2.0"
+    ```
+
+    The data which outputs to kafka follows the binlog format sorted by ts and defined by protobuf. Please refer to [driver](https://github.com/pingcap/tidb-tools/tree/master/tidb_binlog/driver) to access the data and sync to the down stream.
+
 - Deploy Kafka and ZooKeeper cluster before deploying TiDB-Binlog. Make sure that Kafka is 0.9 version or later.
 
 #### Recommended Kafka cluster configuration