fix: use readpartial instead of read to avoid IO blocking

Signed-off-by: Shizuo Fujita <fujita@clear-code.com>

Author: Watson1978

lib/fluent/compat/exec_util.rb

@@ -76,15 +76,18 @@ def each_line(line)
       end
 
       class JSONParser < Parser
+        BYTES_TO_READ = 8192
+
         def call(io)
           parser = JSON::ResumableParser.new({})
-          buffer_size = 8192
-
-          while (chunk = io.read(buffer_size))
-            parser << chunk
-            while parser.parse
-              @on_message.call(parser.value)
+          begin
+            while (chunk = io.readpartial(BYTES_TO_READ))
+              parser << chunk
+              while parser.parse
+                @on_message.call(parser.value)
+              end
             end
+          rescue EOFError
           end
         end
       end

lib/fluent/plugin/parser_json.rb

@@ -92,13 +92,16 @@ def parser_type
 
       def parse_io(io, &block)
         parser = JSON::ResumableParser.new({})
-        while (chunk = io.read(@stream_buffer_size))
-          parser << chunk
+        begin
+          while (chunk = io.readpartial(@stream_buffer_size))
+            parser << chunk
 
-          while parser.parse
-            record = parser.value
-            block.call(parse_time(record), record)
+            while parser.parse
+              record = parser.value
+              block.call(parse_time(record), record)
+            end
           end
+        rescue EOFError
         end
       end
     end