问题
I am trying to access several websites by using Selenium in Java. Occasionally, I get an UnreachableBrowserException. I have read many threads about this error but it seems like there are many different causes of the error. I get the error about 1% of the time when I attempt to access a new page and I cannot find any similarities between occurrences. I currently am using Firefox, however I have also tried Internet Explorer and experienced similar errors. I am only opening one page at a time and have tried using the same window and completely quitting the driver before trying to access another page and either way the error still occurs. It is important to note I do not always get this error sometimes my code can run without this occurring. Here is the error message:
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {}- http://127.0.0.1:7055: Permission denied: connect
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://127.0.0.1:7055
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {}->http://127.0.0.1:7055: Permission denied: connect
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://127.0.0.1:7055
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {}->http://127.0.0.1:7055: Permission denied: connect
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://127.0.0.1:7055
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {}->http://127.0.0.1:7055: Permission denied: connect
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://127.0.0.1:7055
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {}->http://127.0.0.1:7055: Permission denied: connect
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://127.0.0.1:7055
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {}->http://127.0.0.1:7055: Permission denied: connect
Jan 12, 2015 10:39:40 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}->http://127.0.0.1:7055
Exception in thread "main" org.openqa.selenium.remote.UnreachableBrowserException: Error communicating with the remote browser. It may have died.
Build info: version: '2.44.0', revision: '76d78cf', time: '2014-10-23 20:03:00'
System info: host: '****', ip: '**.*.*.*', os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.7.0_60'
Driver info: driver.version: RemoteWebDriver
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:593)
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:614)
at org.openqa.selenium.remote.RemoteWebDriver.quit(RemoteWebDriver.java:468)
at scrape.Scraper.killInstance(Scraper.java:162)
at scrape.Updater.main(Updater.java:93)
Caused by: java.net.SocketException: Permission denied: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at org.apache.http.conn.socket.PlainConnectionSocketFactory.connectSocket(PlainConnectionSocketFactory.java:72)
at org.apache.http.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:123)
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:318)
at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:363)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:219)
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:195)
at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:86)
at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:72)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:57)
at org.openqa.selenium.remote.HttpCommandExecutor.fallBackExecute(HttpCommandExecutor.java:215)
at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:184)
at org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.execute(NewProfileExtensionConnection.java:165)
at org.openqa.selenium.firefox.FirefoxDriver$LazyCommandExecutor.execute(FirefoxDriver.java:362)
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:572)
... 4 more
How can I prevent this error or at least catch the error and deal with it effectively?
回答1:
UnreachableBrowserExceptions can happen for multiple reasons - the most obvious is that the browser was closed, either in code or physically in the GUI, and then the code attempted to access it. Often, like in your case, they are caused by socket errors. This can mean, again, multiple things - your program tried to open too many sockets, it couldn't connect to a remote website, and others.
What I would suggest doing in a situation like this is waiting a short time, then retrying to see if the exception is still thrown. Sometimes these situations resolve themselves and your program can recover.
Here is some code to do that. It keeps retrying as long as the UnreachableBrowserException is thrown and the number of retries is below some limit that you set. If it hits the retry limit and the exception is still being thrown, it closes the browser and restarts it, resetting the retry count to 0. There is also a restart counter, to make sure that if for some reason restarting the browser doesn't help, you don't loop endlessly through running code -> exception -> wait -> retry -> hit retry limit, restart browser -> run code -> exception. Here, exceeding the restart limit (or successfully accessing the browser) will break out of the loop.
If you want more help, let me know.Hope this is helpful!
WebDriver driver = new FirefoxDriver(); //or whatever you're using
boolean worked = false;
int numredos = 0;
final int REDO_LIMIT = 3; //or however many times you want to retry before giving up
final int RESTART_LIMIT = 3; //or however many times you want to restart the browser b/f terminating
int numrestarts = 0;
boolean restart = false;
do
{
try{
if(restart)
{
driver = new FirefoxDriver();
numrestarts++;
}
//RUN YOUR BROWSER CODE HERE
worked = true;
}
//if the browser becomes unreachable (probably b/c of a socket issue),
// write the error to the log and then sleep for 10 seconds
//if we've already retried the set limit number of times, restart the browser and try again
catch (UnreachableBrowserException ube)
{
worked = false;
if(numredos >= REDO_LIMIT)
{
//if you've already restarted the browser too many times, it will set it to null
//and return an error code. If not, it will set the restart flag so it will be restarted on the next iteration.
//try quitting. If it can't do it, it's already dead; just set it to null
//(set it to null either way, just in case)
try
{
driver.quit();
}
catch(Exception j)
{
errorwriter.println(j);
}
driver = null;
if(numrestarts < RESTART_LIMIT)
{
//log that you're restarting the driver (not coded here), then set the restart flag to true. This will cause the browser to be restarted after falling out of the catch block
numredos = 0;
restart = true;
}
}
else
{
//print details of the exception to the error file
errorfile.println("\n\n\n");
//timestamp, and some exception details - you can decide which you want
errorfile.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(Calendar.getInstance().getTime()));
errorfile.println(s.getClass());
errorfile.println(s.getMessage());
errorfile.println("Cause: " + s.getCause());
errorfile.flush();
//now sleep for some number of seconds - here 10
try
{
TimeUnit.SECONDS.sleep(10);
}
catch(InterruptedException e)
{
System.out.println("waiting after socket crash interrupted");
}
numredos++;
}
}
}while(!worked && numredos <= REDO_LIMIT && numrestarts <= RESTART_LIMIT);
来源：https://stackoverflow.com/questions/27926058/selenium-occasional-unreachablebrowserexception