From 0afb44445831c576c51b7ef95f58fafeb5a794ff Mon Sep 17 00:00:00 2001
From: zhangxin10 <curtain.xin@gmail.com>
Date: Mon, 14 Dec 2015 16:03:09 +0800
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---
 .../sender/DataSenderFactoryWithBalance.java         | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/skywalking-api/src/main/java/com/ai/cloud/skywalking/sender/DataSenderFactoryWithBalance.java b/skywalking-api/src/main/java/com/ai/cloud/skywalking/sender/DataSenderFactoryWithBalance.java
index a00570e9d..3397f9729 100644
--- a/skywalking-api/src/main/java/com/ai/cloud/skywalking/sender/DataSenderFactoryWithBalance.java
+++ b/skywalking-api/src/main/java/com/ai/cloud/skywalking/sender/DataSenderFactoryWithBalance.java
@@ -140,8 +140,16 @@ public class DataSenderFactoryWithBalance {
                     if (usingDataSender.size() >= maxKeepConnectingSenderSize) {
                         DataSender toBeSwitchSender;
                         DataSender tmpSender;
-                        int toBeSwitchIndex = ThreadLocalRandom.current()
-                                .nextInt(0, usingDataSender.size() - 1);
+
+                        int toBeSwitchIndex;
+
+                        if (usingDataSender.size() - 1 > 0) {
+                            toBeSwitchIndex = ThreadLocalRandom.current()
+                                    .nextInt(0, usingDataSender.size() - 1);
+                        } else {
+                            toBeSwitchIndex = 0;
+                        }
+
                         toBeSwitchSender = usingDataSender.get(toBeSwitchIndex);
                         tmpSender = findReadySender();
                         if (tmpSender != null) {