NoHttpResponseException异常解决优化HttpClient配置以避免连接问题
目录
- 序
- NoHttpResponseException
- DefaultHttpResponseParser
- 小结
序
本文主要研究一下HttpClient的NoHttpResponseException
NoHttpRespwww.devze.comonseException
org/apache/http/NoHttpResponseException.Java
/** * Signals that the target server failed to respond with a valid HTTP response. * * @since 4.0 */ public class NoHttpResponseException extends IOException { private static final long serialVersionUID = -7658940387386078766L; /** * Creates a new NoHttpResponseExcepythonption with the specified detail message. * * @param message except编程ion message */ public NoHttpResponseException(final String message) { super(HttpException.clean(message)); } }
NoHttpResponseException继承了IOException,用于表示目标服务器没有返回一个正常的http response
DefaultHttpResponseParser
org/apache/http/impl/conn/DefaultHttpResponseParser.jhttp://www.devze.comava
public class DefaultHttpResponseParser extends AbstractMessageParser<HttpResponse> { private final Log log = LogFactory.getLog(getClass()); private final HttpResponseFactory responseFactory; private final CharArrayBuffer lineBuf; //...... @Override protected HttpResponse parseHead( final SessionInputBuffer sessionBuffer) throws IOException, HttpException { //read out the HTTP status string int count = 0; ParserCursor cursor = null; do { // clear the buffer this.lineBuf.clear(); final int i = sessionBuffer.readLine(this.lineBuf); if (i == -1 && count == 0) { // The server just dropped connection on us throw AGhQDIqrlvnew NoHttpResponseException("The target server failed to respond"); } cursor = new ParserCursor(0, this.lineBuf.length()); if (lineParser.hASProtocolVersion(this.lineBuf, cursor)) { // Got one break; } else if (i == -1 || reject(this.lineBuf, count)) { // Giving up throw new ProtocolException("The server failed to respond with a " + "valid HTTP response"); } if (this.log.isDebugEnabled()) { this.log.debug("Garbage in response: " + this.lineBuf.toString()); } count++; } while(true); //create the status line from the status string final StatusLine statusline = lineParser.parseStatusLine(this.lineBuf, cursor); return this.responseFactory.newHttpResponse(statusline, null); } protected boolean reject(final CharArrayBuffer line, final int count) { return false; } }
DefaultHttpResponseParser继承了AbstractMessageParser,其parseHead方法读取sessionBuffer,若该数据为空则抛出NoHttpResponseException("The target server failed to respond")
小结
NoHttpResponseException继承了IOException,用于表示目标服务器没有返回一个正常的http response,一般是目标服务器负载太高处理不过来因而断开了连接,也有可能是目标服务器把这个空闲连接关闭了,而HttpClient则继续用这个连接发送请求则会读取不到正常的reponse,因而抛出NoHttpResponseException。大多数情况下,可以通过重试解决。另外针对因为keep-alive超时断开的,可以配置HttpClient的connTimeToLive值小于服务端的keepAlive值(通常是60s)。
doc
- Exception handling
- 生产环境NoHttpResponseException异常排查记录
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