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How do I make a Java function that retries a URL connection every half second if the connection takes too long?

So I have a problem with a Java program I have. The program's basic functionality includes basically connecting to a web API for data. The function that does that is something like this:
public static Object getData(String sURL) throws IOException {
URL url = new URL(sURL);
URLConnection request = url.openConnection();
request.connect();
return request.getContent();
}
The code works fine as it is, but recently, after my house changed ISPs, I have found that sometimes the connections take an unreasonably long amount of time, something like 10 seconds or more in about 10% of attempts, while the other 90% takes only around 200ms. I have found it to be faster to ask my program to call the function again in a different thread than to wait for some of these connections to finally connect.
Therefore, I want to change the function so that if after 500ms, the connection did not establish, it would disconnect and a new connection would be attempted. How could I do this?
Somewhere online I read that HttpURLConnection might help, but I am not sure how.

URLConnection allows you to specify the connect and read timeout prior to calling connect():
https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/URLConnection.html#setConnectTimeout(int)
Sets a specified timeout value, in milliseconds, to be used when
opening a communications link to the resource referenced by this
URLConnection. If the timeout expires before the connection can be
established, a java.net.SocketTimeoutException is raised. A timeout of
zero is interpreted as an infinite timeout.
With 500ms timeout:
try {
URLConnection request = url.openConnection();
request.setConnectTimeout(500); // 500 ms
request.connect();
// on successful connection
} catch (SocketTimeoutException ex) {
// on request timeout
}
This you can pack into a loop, but I recommend limiting the number of attempts made.

Java's URLConnection doesn't have retry capabilities in Java 8 therefore the best way here to achieve this - use an appropriate standalone 3-party library such as Apache HttpClient.
This is by far the best standalone 3-party HTTP client with advanced capabilities as of 2020 and it's still maintained.
By default as of version 5.2.x Apache Http Client, Apache Http Client uses the default implementation of org.apache.http.client.HttpRequestRetryHandler, which retries 3 times, but you can use a custom implementation instead.
The configuration might look like this(full imports are for example's sake):
org.apache.http.client.HttpClient httpClient = org.apache.http.impl.client.HttpClients.custom()
.setRetryHandler(YourCustomImplOfTheRetryHandlerClass)
//other config
.build();

There is no way I can reproduce that problem using my ISP.
I suggest you dig deeper into the problem and find a better solution. Sending another request just doesn't seem good enough to me. Maybe try a different way to get the data and see if that works for you. Can't say for sure as I can't reproduce the problem.

httpclient Connection reset [duplicate]

I'm creating a (well behaved) web spider and I notice that some servers are causing Apache HttpClient to give me a SocketException -- specifically:
java.net.SocketException: Connection reset
The code that causes this is:
// Execute the request
HttpResponse response;
try {
response = httpclient.execute(httpget); //httpclient is of type HttpClient
} catch (NullPointerException e) {
return;//deep down in apache http sometimes throws a null pointer...
}
For most servers it's just fine. But for others, it immediately throws a SocketException.
Example of site that causes immediate SocketException: http://www.bhphotovideo.com/
Works great (as do most websites): http://www.google.com/
Now, as you can see, www.bhphotovideo.com loads fine in a web browser. It also loads fine when I don't use Apache's HTTP Client. (Code like this:)
HttpURLConnection c = (HttpURLConnection)url.openConnection();
BufferedInputStream in = new BufferedInputStream(c.getInputStream());
Reader r = new InputStreamReader(in);
int i;
while ((i = r.read()) != -1) {
source.append((char) i);
}
So, why don't I just use this code instead? Well there are some key features in Apache's HTTP Client that I need to use.
Does anyone know what causes some servers to cause this exception?
Research so far:
Problem occurs on my local Mac dev machines AND an AWS EC2 Instance, so it's not a local firewall.
It seems the error isn't caused by the remote machine because the exception doesn't say "by peer"
This stack overflow seems relavent java.net.SocketException: Connection reset but the answers don't show why this would happen only from Apache HTTP Client and not other approaches.
Bonus question: I'm doing a fair amount of crawling with this system. Is there generally a better Java class for this other than Apache HTTP Client? I've found a number of issues (such as the NullPointerException I have to catch in the code above). It seems that HTTPClient is very picky about server communications -- more picky than I'd like for a crawler that can't just break when a server doesn't behave.
Thanks all!
Solution
Honestly, I don't have a perfect solution, but it works, so that's good enough for me.
As pointed out by oleg below, Bixo has created a crawler that customizes HttpClient to be more forgiving to servers. To "get around" the issue more than fix it, I just used SimpleHttpFetcher provided by Bixo here:
(linked removed - SO thinks I'm a spammer, so you'll have to google it yourself)
SimpleHttpFetcher fetch = new SimpleHttpFetcher(new UserAgent("botname","contact#yourcompany.com","ENTER URL"));
try {
FetchedResult result = fetch.fetch("ENTER URL");
System.out.println(new String(result.getContent()));
} catch (BaseFetchException e) {
e.printStackTrace();
}
The down side to this solution is that there are a lot of dependencies for Bixo -- so this may not be a good work around for everyone. However, you can always just work through their use of DefaultHttpClient and see how they instantiated it to get it to work. I decided to use the whole class because it handles some things for me, like automatic redirect following (and reporting the final destination url) that are helpful.
Thanks for the help all.
Edit: TinyBixo
Hi all. So, I loved how Bixo worked, but didn't like that it had so many dependencies (including all of Hadoop). So, I created a vastly simplified Bixo, without all the dependencies. If you're running into the problems above, I would recommend using it (and feel free to make pull requests if you'd like to update it!)
It's available here: https://github.com/juliuss/TinyBixo

First, to answer your question:
The connection reset was caused by a problem on the server side. Most likely the server failed to parse the request or was unable to process it and dropped the connection as a result without returning a valid response. There is likely something in the HTTP requests generated by HttpClient that causes server side logic to fail, probably due to a server side bug. Just because the error message does not say 'by peer' does not mean the connection reset took place on the client side.
A few remarks:
(1) Several popular web crawlers such as bixo http://openbixo.org/ use HttpClient without major issues but pretty much of them had to tweak HttpClient behavior to make it more lenient about common HTTP protocol violations. Per default HttpClient is rather strict about the HTTP protocol compliance.
(2) Why did not you report the NPE problem or any other problem you have been experiencing to the HttpClient project?

These two settings will sometimes help:
client.getParams().setParameter("http.socket.timeout", new Integer(0));
client.getParams().setParameter("http.connection.stalecheck", new Boolean(true));
The first sets the socket timeout to be infinite.

Try getting a network trace using wireshark, and augment that with log4j logging of the HTTPClient. That should show why the connection is being reset

HttpURLConnection slow to disconnect - Java / Android

I want to get the file size of a file on a remote connection without actually downloading the (large) file. I am using the "Content-Length" header of the file. The relevant code is:
URL obj = new URL(FILES_URL + fileName);
String contentLength = "";
HttpURLConnection conn = null;
try {
conn = (HttpURLConnection) obj.openConnection();
conn.setConnectTimeout(3000);
conn.setReadTimeout(3000);
contentLength = conn.getHeaderField("Content-Length");
int responseCode = conn.getResponseCode();
Log.d(TAG, "responseCode: " + responseCode);
} finally {
Log.d(TAG, "pre-disconnect");
if (conn!=null) conn.disconnect();
Log.d(TAG, "post-disconnect");
}
return contentLength;
The command "conn.disconnect();" sometimes seems to take forever. I have seen 23 seconds! Admittedly, this is connecting to a secondary local device which is running a web server, but the WiFi signal is strong, relatively fast, and I have never had any such problems using "curl" from my laptop. I do not have control over the web server I am connecting too.
The problem possibly is enhanced when making multiple similar connections to different files one after another, not sure. This is, however, creating entirely new HttpURLConnection's and not reusing the old one. Could reusing the connection help?
I never actually download the file or access the inputstream.
I could just not call disconnect, but I understand it is not recommended because resources would not be released. Is this not correct? I notice URLConnection doesn't have a disconnect. It is just suggested to close any streams you open.
This code is in an asynctask. I guess I could try moving the disconnect call itself to a further asynctask because I don't do anything afterwards. Not sure if that is even possible.
Do you have any suggestions? Should I try something other than HttpURLConnection to get the file size without downloading the file?

Thanks to EJP in the comments. Changing the request method to "HEAD" made the disconnect almost instantaneous:
conn.setRequestMethod("HEAD");
From what I have read, HttpURLConnection.disconnect() will skip through the entire response object if it hasn't been read. Therefore, for very large files, it will take a long time. Using the request method "HEAD" force the response body to be empty and solves the issue.

I suggest you to use either Volley or Okhttp for faster networking but depending on your requirement . Got through Comparison Of Volley And OkHttp and Retrofit and decide which library to use.
As suggestion if you putting this code inside AsyncTask then Read Dark Side of AsyncTask.

Apache HTTPClient throws java.net.SocketException: Connection reset for many domains

I'm creating a (well behaved) web spider and I notice that some servers are causing Apache HttpClient to give me a SocketException -- specifically:
java.net.SocketException: Connection reset
The code that causes this is:
// Execute the request
HttpResponse response;
try {
response = httpclient.execute(httpget); //httpclient is of type HttpClient
} catch (NullPointerException e) {
return;//deep down in apache http sometimes throws a null pointer...
}
For most servers it's just fine. But for others, it immediately throws a SocketException.
Example of site that causes immediate SocketException: http://www.bhphotovideo.com/
Works great (as do most websites): http://www.google.com/
Now, as you can see, www.bhphotovideo.com loads fine in a web browser. It also loads fine when I don't use Apache's HTTP Client. (Code like this:)
HttpURLConnection c = (HttpURLConnection)url.openConnection();
BufferedInputStream in = new BufferedInputStream(c.getInputStream());
Reader r = new InputStreamReader(in);
int i;
while ((i = r.read()) != -1) {
source.append((char) i);
}
So, why don't I just use this code instead? Well there are some key features in Apache's HTTP Client that I need to use.
Does anyone know what causes some servers to cause this exception?
Research so far:
Problem occurs on my local Mac dev machines AND an AWS EC2 Instance, so it's not a local firewall.
It seems the error isn't caused by the remote machine because the exception doesn't say "by peer"
This stack overflow seems relavent java.net.SocketException: Connection reset but the answers don't show why this would happen only from Apache HTTP Client and not other approaches.
Bonus question: I'm doing a fair amount of crawling with this system. Is there generally a better Java class for this other than Apache HTTP Client? I've found a number of issues (such as the NullPointerException I have to catch in the code above). It seems that HTTPClient is very picky about server communications -- more picky than I'd like for a crawler that can't just break when a server doesn't behave.
Thanks all!
Solution
Honestly, I don't have a perfect solution, but it works, so that's good enough for me.
As pointed out by oleg below, Bixo has created a crawler that customizes HttpClient to be more forgiving to servers. To "get around" the issue more than fix it, I just used SimpleHttpFetcher provided by Bixo here:
(linked removed - SO thinks I'm a spammer, so you'll have to google it yourself)
SimpleHttpFetcher fetch = new SimpleHttpFetcher(new UserAgent("botname","contact#yourcompany.com","ENTER URL"));
try {
FetchedResult result = fetch.fetch("ENTER URL");
System.out.println(new String(result.getContent()));
} catch (BaseFetchException e) {
e.printStackTrace();
}
The down side to this solution is that there are a lot of dependencies for Bixo -- so this may not be a good work around for everyone. However, you can always just work through their use of DefaultHttpClient and see how they instantiated it to get it to work. I decided to use the whole class because it handles some things for me, like automatic redirect following (and reporting the final destination url) that are helpful.
Thanks for the help all.
Edit: TinyBixo
Hi all. So, I loved how Bixo worked, but didn't like that it had so many dependencies (including all of Hadoop). So, I created a vastly simplified Bixo, without all the dependencies. If you're running into the problems above, I would recommend using it (and feel free to make pull requests if you'd like to update it!)
It's available here: https://github.com/juliuss/TinyBixo

First, to answer your question:
The connection reset was caused by a problem on the server side. Most likely the server failed to parse the request or was unable to process it and dropped the connection as a result without returning a valid response. There is likely something in the HTTP requests generated by HttpClient that causes server side logic to fail, probably due to a server side bug. Just because the error message does not say 'by peer' does not mean the connection reset took place on the client side.
A few remarks:
(1) Several popular web crawlers such as bixo http://openbixo.org/ use HttpClient without major issues but pretty much of them had to tweak HttpClient behavior to make it more lenient about common HTTP protocol violations. Per default HttpClient is rather strict about the HTTP protocol compliance.
(2) Why did not you report the NPE problem or any other problem you have been experiencing to the HttpClient project?

These two settings will sometimes help:
client.getParams().setParameter("http.socket.timeout", new Integer(0));
client.getParams().setParameter("http.connection.stalecheck", new Boolean(true));
The first sets the socket timeout to be infinite.

Try getting a network trace using wireshark, and augment that with log4j logging of the HTTPClient. That should show why the connection is being reset

java.net.SocketException: Software caused connection abort: recv failed

I haven't been able to find an adequate answer to what exactly the following error means:
java.net.SocketException: Software caused connection abort: recv failed
Notes:
This error is infrequent and unpredictable; although getting this error means that all future requests for URIs will also fail.
The only solution that works (also, only occasionally) is to reboot Tomcat and/or the actual machine (Windows in this case).
The URI is definitely available (as confirmed by asking the browser to do the fetch).
Relevant code:
BufferedReader reader;
try {
URL url = new URL(URI);
reader = new BufferedReader(new InputStreamReader(url.openStream())));
} catch( MalformedURLException e ) {
throw new IOException("Expecting a well-formed URL: " + e);
}//end try: Have a stream
String buffer;
StringBuilder result = new StringBuilder();
while( null != (buffer = reader.readLine()) ) {
result.append(buffer);
}//end while: Got the contents.
reader.close();

This also happens if your TLS client is unable to be authenticate by the server configured to require client authentication.

This usually means that there was a network error, such as a TCP timeout. I would start by placing a sniffer (wireshark) on the connection to see if you can see any problems. If there is a TCP error, you should be able to see it. Also, you can check your router logs, if this is applicable. If wireless is involved anywhere, that is another source for these kind of errors.

This error occurs when a connection is closed abruptly (when a TCP connection is reset while there is still data in the send buffer). The condition is very similar to a much more common 'Connection reset by peer'. It can happen sporadically when connecting over the Internet, but also systematically if the timing is right (e.g. with keep-alive connections on localhost).
An HTTP client should just re-open the connection and retry the request. It is important to understand that when a connection is in this state, there is no way out of it other than to close it. Any attempt to send or receive will produce the same error.
Don't use URL.open(), use Apache-Commons HttpClient which has a retry mechanism, connection pooling, keep-alive and many other features.
Sample usage:
HttpClient httpClient = HttpClients.custom()
.setConnectionTimeToLive(20, TimeUnit.SECONDS)
.setMaxConnTotal(400).setMaxConnPerRoute(400)
.setDefaultRequestConfig(RequestConfig.custom()
.setSocketTimeout(30000).setConnectTimeout(5000).build())
.setRetryHandler(new DefaultHttpRequestRetryHandler(5, true))
.build();
// the httpClient should be re-used because it is pooled and thread-safe.
HttpGet request = new HttpGet(uri);
HttpResponse response = httpClient.execute(request);
reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
// handle response ...

Are you accessing http data? Can you use the HttpClient library instead of the standard library? The library has more options and will provide better error messages.
http://hc.apache.org/httpclient-3.x/

The only time I've seen something like this happen is when I have a bad connection, or when somebody is closing the socket that I am using from a different thread context.

Try adding 'autoReconnect=true' to the jdbc connection string

This will happen from time to time either when a connection times out or when a remote host terminates their connection (closed application, computer shutdown, etc). You can avoid this by managing sockets yourself and handling disconnections in your application via its communications protocol and then calling shutdownInput and shutdownOutput to clear up the session.

Look if you have another service or program running on the http port. It happened to me when I tried to use the port and it was taken by another program.

If you are using Netbeans to manage Tomcat, try to disable HTTP monitor in Tools - Servers

I too had this problem. My solution was:
sc.setSoLinger(true, 10);
COPY FROM A WEBSITE -->By using the setSoLinger() method, you can explicitly set a delay before a reset is sent, giving more time for data to be read or send.
Maybe it is not the answer to everybody but to some people.