replace LinkedList by ArrayList in BufferedProducerKtImpl (#156)

Author: daleiz

client/build.gradle.kts

@@ -178,7 +178,7 @@ tasks.withType<Javadoc> {
     (options as StandardJavadocDocletOptions).addBooleanOption("html5", true)
     (options as StandardJavadocDocletOptions).links(
         "https://docs.oracle.com/en/java/javase/11/docs/api/",
-        "https://javadoc.io/doc/com.google.guava/guava/latest/"
+        // "https://javadoc.io/doc/com.google.guava/guava/latest/"
     )
     exclude("io/hstream/impl/**", "io/hstream/util/**")
 }

client/src/main/kotlin/io/hstream/impl/BufferedProducerKtImpl.kt

@@ -66,8 +66,8 @@ class BufferedProducerKtImpl(
             val partitionKey = hStreamRecord.header.key
             val shardId = calculateShardIdByPartitionKey(partitionKey)
             if (!shardAppendBuffer.containsKey(shardId)) {
-                shardAppendBuffer[shardId] = LinkedList()
-                shardAppendFutures[shardId] = LinkedList()
+                shardAppendBuffer[shardId] = ArrayList()
+                shardAppendFutures[shardId] = ArrayList()
                 shardAppendBytesSize[shardId] = 0
                 if (batchSetting.ageLimit > 0) {
                     timerServices[shardId] =