Merge pull request #90 from fluent/follow-up-86

Update pool parameter. ref #86

Author: repeatedly

lib/fluent/plugin/out_sql.rb

@@ -29,7 +29,8 @@ class SQLOutput < Output
     config_param :remove_tag_prefix, :string, default: nil
     desc 'enable fallback'
     config_param :enable_fallback, :bool, default: true
-    config_param :pool, :integer, default: 10
+    desc "size of ActiveRecord's connection pool"
+    config_param :pool, :integer, default: 5
     desc "specifies the timeout to establish a new connection to the database before failing"
     config_param :timeout, :integer, default: 5000
 
@@ -175,6 +176,10 @@ def configure(conf)
         end
       }
 
+      if @pool < @buffer_config.flush_thread_count
+        log.warn "connection pool size is smaller than buffer's flush_thread_count. Recommend to increase pool value", :pool => @pool, :flush_thread_count => @buffer_config.flush_thread_count
+      end
+
       if @default_table.nil?
         raise Fluent::ConfigError, "There is no default table. <table> is required in sql output"
       end

test/plugin/test_out_sql.rb

@@ -43,7 +43,8 @@ def test_configure
       password: "fluentd",
       schema_search_path: 'public',
       remove_tag_suffix: /^db/,
-      enable_fallback: true
+      enable_fallback: true,
+      pool: 5
     }
     actual = {
       host: d.instance.host,
@@ -54,7 +55,8 @@ def test_configure
       password: d.instance.password,
       schema_search_path: d.instance.schema_search_path,
       remove_tag_suffix: d.instance.remove_tag_prefix,
-      enable_fallback: d.instance.enable_fallback
+      enable_fallback: d.instance.enable_fallback,
+      pool: d.instance.pool
     }
     assert_equal(expected, actual)
     assert_empty(d.instance.tables)