diff --git a/benchmarks/src/main/java/com/esotericsoftware/kryo/benchmarks/io/HugeStringBenchmark.java b/benchmarks/src/main/java/com/esotericsoftware/kryo/benchmarks/io/HugeStringBenchmark.java
new file mode 100644
index 000000000..bcf7aaf17
--- /dev/null
+++ b/benchmarks/src/main/java/com/esotericsoftware/kryo/benchmarks/io/HugeStringBenchmark.java
@@ -0,0 +1,50 @@
+/* Copyright (c) 2008-2020, Nathan Sweet
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
+ * conditions are met:
+ * 
+ * - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided with the distribution.
+ * - Neither the name of Esoteric Software nor the names of its contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
+
+package com.esotericsoftware.kryo.benchmarks.io;
+
+import com.esotericsoftware.kryo.io.Output;
+import org.openjdk.jmh.annotations.*;
+
+
+
+
+/*
+ * this benchmark is used to test serialize huge string when not reuse the buffer
+ * */
+@BenchmarkMode(Mode.SingleShotTime)
+@Measurement(batchSize = 120000)
+public class HugeStringBenchmark {
+	static String hugeString = "";
+	static {
+		for(int i = 0; i < 256; i++){
+			hugeString += "abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456789";
+		}
+	}
+	
+	/**
+	 * 1. not reuse the output
+	 * 2. the initial bufferSize will be smaller than hugeString size
+	 * ***/
+	@Benchmark
+	public void writeAsciiHuge (InputOutputState state) {
+		Output output = new Output(1024, 1024 * 512);
+		output.writeAscii(hugeString);
+	}
+}
\ No newline at end of file
diff --git a/src/com/esotericsoftware/kryo/io/ByteBufferOutput.java b/src/com/esotericsoftware/kryo/io/ByteBufferOutput.java
index c3cb14769..d2efc4ba5 100644
--- a/src/com/esotericsoftware/kryo/io/ByteBufferOutput.java
+++ b/src/com/esotericsoftware/kryo/io/ByteBufferOutput.java
@@ -649,7 +649,7 @@ private void writeAscii_slow (String value, int charCount) throws KryoException
 			buffer.put(tmp, 0, charsToWrite);
 			charIndex += charsToWrite;
 			position += charsToWrite;
-			charsToWrite = Math.min(charCount - charIndex, capacity);
+			charsToWrite = Math.min(charCount - charIndex, maxAvailableRequired());
 			if (require(charsToWrite)) buffer = this.byteBuffer;
 		}
 	}
diff --git a/src/com/esotericsoftware/kryo/io/Output.java b/src/com/esotericsoftware/kryo/io/Output.java
index 6a8aa1289..fc78f5cd8 100644
--- a/src/com/esotericsoftware/kryo/io/Output.java
+++ b/src/com/esotericsoftware/kryo/io/Output.java
@@ -173,7 +173,13 @@ public void reset () {
 		position = 0;
 		total = 0;
 	}
-
+	
+	/**how much space can be allocated when call require **/
+	public int maxAvailableRequired(){
+		if(outputStream != null){return maxCapacity;}
+		else{return maxCapacity - position;}
+	}
+	
 	/** Ensures the buffer is large enough to read the specified number of bytes.
 	 * @return true if the buffer has been resized. */
 	protected boolean require (int required) throws KryoException {
@@ -746,7 +752,7 @@ private void writeAscii_slow (String value, int charCount) throws KryoException
 			value.getBytes(charIndex, charIndex + charsToWrite, buffer, position);
 			charIndex += charsToWrite;
 			position += charsToWrite;
-			charsToWrite = Math.min(charCount - charIndex, capacity);
+			charsToWrite = Math.min(charCount - charIndex, maxAvailableRequired());
 			if (require(charsToWrite)) buffer = this.buffer;
 		}
 	}