Java线上应用故障排查之一：高CPU占用

 1  public byte[] readBytes(int length) throws IOException {
 2 
 3     if ((this.socket == null) || (!this.socket.isConnected())) {
 4 
 5         throw new IOException("++++ attempting to read from closed socket");
 6 
 7     }
 8 
 9     byte[] result = null;
10 
11     ByteArrayOutputStream bos = new ByteArrayOutputStream();
12 
13     if (this.recIndex >= length) {
14 
15            bos.write(this.recBuf, 0, length);
16 
17            byte[] newBuf = new byte[this.recBufSize];
18 
19            if (this.recIndex > length) {
20 
21                System.arraycopy(this.recBuf, length, newBuf, 0, this.recIndex - length);
22 
23            }
24 
25            this.recBuf = newBuf;
26 
27            this.recIndex -= length;
28 
29     } else {
30 
31            int totalread = length;
32 
33            if (this.recIndex > 0) {
34 
35                 totalread -= this.recIndex;
36 
37                 bos.write(this.recBuf, 0, this.recIndex);
38 
39                 this.recBuf = new byte[this.recBufSize];
40 
41                 this.recIndex = 0;
42 
43     }
44 
45     int readCount = 0;
46 
47     while (totalread > 0) {
48 
49          if ((readCount = this.in.read(this.recBuf)) > 0) {
50 
51                 if (totalread > readCount) {
52 
53                       bos.write(this.recBuf, 0, readCount);
54 
55                       this.recBuf = new byte[this.recBufSize];
56 
57                       this.recIndex = 0;
58 
59                } else {
60 
61                      bos.write(this.recBuf, 0, totalread);
62 
63                      byte[] newBuf = new byte[this.recBufSize];
64 
65                      System.arraycopy(this.recBuf, totalread, newBuf, 0, readCount - totalread);
66 
67                      this.recBuf = newBuf;
68 
69                      this.recIndex = (readCount - totalread);
70 
71              }
72 
73              totalread -= readCount;
74 
75         }
76 
77    }
78 
79 }