diff --git a/lib/fluent/plugin/out_exec_filter.rb b/lib/fluent/plugin/out_exec_filter.rb
index 2bcda92615..2dec7997dd 100644
--- a/lib/fluent/plugin/out_exec_filter.rb
+++ b/lib/fluent/plugin/out_exec_filter.rb
@@ -95,6 +95,7 @@ class ExecFilterOutput < Output
     COMPAT_PARSE_PARAMS = {
       'out_format' => '@type',
       'out_keys' => 'keys',
+      'out_stream_buffer_size' => 'stream_buffer_size',
     }
     COMPAT_EXTRACT_PARAMS = {
       'out_tag_key' => 'tag_key',
diff --git a/lib/fluent/plugin/parser_json.rb b/lib/fluent/plugin/parser_json.rb
index 50a80a31c9..49f5584d08 100644
--- a/lib/fluent/plugin/parser_json.rb
+++ b/lib/fluent/plugin/parser_json.rb
@@ -30,6 +30,12 @@ class JSONParser < Parser
       desc 'Set JSON parser'
       config_param :json_parser, :enum, list: [:oj, :yajl, :json], default: :oj
 
+      # The Yajl library defines a default buffer size of 8092 when parsing
+      # from IO streams, so maintain this for backwards-compatibility.
+      # https://www.rubydoc.info/github/brianmario/yajl-ruby/Yajl%2FParser:parse
+      desc 'Set the buffer size that Yajl will use when parsing streaming input'
+      config_param :stream_buffer_size, :integer, default: 8092
+
       config_set_default :time_type, :float
 
       def configure(conf)
@@ -81,7 +87,7 @@ def parse_io(io, &block)
         y.on_parse_complete = ->(record){
           block.call(parse_time(record), record)
         }
-        y.parse(io)
+        y.parse(io, @stream_buffer_size)
       end
     end
   end
diff --git a/test/plugin/test_out_exec_filter.rb b/test/plugin/test_out_exec_filter.rb
index 8d9be9f1fa..d3ced55c2c 100644
--- a/test/plugin/test_out_exec_filter.rb
+++ b/test/plugin/test_out_exec_filter.rb
@@ -328,6 +328,7 @@ def create_driver(conf)
     </format>
     <parse>
       @type json
+      stream_buffer_size 1
     </parse>
     <extract>
       tag_key tag
@@ -338,6 +339,7 @@ def create_driver(conf)
     command cat
     in_keys message
     out_format json
+    out_stream_buffer_size 1
     time_key time
     tag_key tag
   ]
@@ -372,6 +374,7 @@ def create_driver(conf)
     </format>
     <parse>
       @type json
+      stream_buffer_size 1
     </parse>
     <extract>
       tag_key tag
@@ -382,6 +385,7 @@ def create_driver(conf)
     command cat
     in_keys message
     out_format json
+    out_stream_buffer_size 1
     time_key time
     tag_key tag
   ]
@@ -414,6 +418,7 @@ def create_driver(conf)
     </format>
     <parse>
       @type json
+      stream_buffer_size 1
     </parse>
     <extract>
       tag_key tag
@@ -426,6 +431,7 @@ def create_driver(conf)
     command cat
     in_keys message
     out_format json
+    out_stream_buffer_size 1
     time_key time
     time_format %d/%b/%Y %H:%M:%S.%N %z
     tag_key tag
diff --git a/test/plugin/test_parser_json.rb b/test/plugin/test_parser_json.rb
index 46c5f47d9f..19c45402d1 100644
--- a/test/plugin/test_parser_json.rb
+++ b/test/plugin/test_parser_json.rb
@@ -111,4 +111,28 @@ def test_parse_with_keep_time_key_without_time_format(data)
       assert_equal text, record['time']
     end
   end
+
+  def test_yajl_parse_io_with_buffer_smaller_than_input
+    parser = Fluent::Test::Driver::Parser.new(Fluent::Plugin::JSONParser)
+    parser.configure(
+                     'keep_time_key' => 'true',
+                     'json_parser' => 'yajl',
+                     'stream_buffer_size' => 1,
+                     )
+    text = "100"
+
+    waiting(5) do
+      rd, wr = IO.pipe
+      wr.write "{\"time\":\"#{text}\"}"
+
+      parser.instance.parse_io(rd) do |time, record|
+        assert_equal text.to_i, time.sec
+        assert_equal text, record['time']
+
+        # Once a record has been received the 'write' end of the pipe must be
+        # closed, otherwise the test will block waiting for more input.
+        wr.close
+      end
+    end
+  end
 end