diff --git a/src/docs/erlang/etsmatch.hrl.md b/src/docs/erlang/etsmatch.hrl.md
index 57c0e34..1ef15c3 100644
--- a/src/docs/erlang/etsmatch.hrl.md
+++ b/src/docs/erlang/etsmatch.hrl.md
@@ -18,4 +18,16 @@
 -type nonCompositeTerm() :: term(). %%   (not list or tuple or map)
 -type constant() :: {const, term()}.
 -type guardFunction() :: boolFunction() | abs | element | hd | length | map_get | map_size | node | round | size | bit_size | tl | trunc | '+' | '-' | '*' | 'div' | 'rem' | 'band' | 'bor' | 'bxor' | 'bnot' | 'bsl' | 'bsr' | '>' | '>=' | '<' | '=<' | '=:=' | '==' | '=/=' | '/=' | self.
--type matchBody() :: [ conditionExpression(), ... ].
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+-type matchBody() :: [ conditionExpression(), ... ].
+
+ets表并发写优化
+    1.核心思想还是避免数据写操作是并发操作 这种可以将ets 设置为bag 相当于有主key 是并发的 然后次key的拥有者只能自己写自己的数据
+    2. 使用ets:select_replace 实现无锁替换操作
+        update_with_fun(Table, Key, Fun) ->
+            [Old] = ets:lookup(Table, Key),
+            New = Fun(Old),
+            Success = (1 =:= ets:select_replace(Table, [{Old, [], [{const, New}]}])),
+            case Success of
+            true -> New;
+            false -> update_with_fun(Table, Key, Fun)
+        end.
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