Okhttp3 set timeout is useless

Question

OkHttpClient client;

client = new OkHttpClient.Builder()
        .connectTimeout(5, TimeUnit.SECONDS)
        .writeTimeout(5, TimeUnit.SECONDS)
        .readTimeout(5, TimeUnit.SECONDS)
        .build();

Request request22 = new Request.Builder()
        .url("http://www.goo.com/")
        .build();

Utils.myLog("-begin-");
Response response = null;
try {
    response = client.newCall(request22).execute();
    if (response.isSuccessful()) {
        Utils.myLog("-donw-");
    }
} catch (Exception e) {
    e.printStackTrace();
    Utils.myLog("-error-" + e.toString());
}

This is my code, I have set timeout to 5 seconds, but it still taked 20 seconds to receive "error unknownhostexception " after "begin"? why my code is useless? I have looked the source code of OKHTTP, default timeout is 10 seconds(if I'm right), I'm confused.

Anyone can help, id really appreciated.

An error message mentioning “unknown host” probably indicates DNS resolver issues: 20 seconds may refer to DNS timeout (DNS resolvers simply do not reply when they [still] have no answer) rather than TCP handshake timeout. I would start with finding out how does your software framework contact name servers and/or checking your particular network configuration. — Anton Samsonov, Dec 25 '16 at 09:32
@AntonSamsonov thank you for answering! If there is no way to avoid DNS problem, How to set timeout no matter what exception? Thanks again! — angryd, Dec 25 '16 at 09:49
For a regular GNU/Linux system, one can configure DNS attempts and timeouts in [/etc/resolv.conf](https://en.wikipedia.org/wiki/Resolv.conf), although I strongly recommend against that, as default DNS timings are a de-facto standard. However, on Android such configuration is unlikely to be available. Moreover, OkHttp may use its own Java-based resolver (I am familiar with neither OkHttp nor Java, just imagining all the possibilities), so you may need to influence that resolver rather than the system-provided service. — Anton Samsonov, Dec 25 '16 at 10:00
@angryd please have to look at this [answer](https://stackoverflow.com/questions/55122236/okhttp3-never-timeout-on-slow-internet) its working fine for me. — Tanveer Munir, Mar 15 '19 at 13:25

Dmitry Zenovich · Answer 1 · 2019-01-30T16:14:26.197

4

For now, OkHttp can't interrupt time-consuming DNS requests (see https://github.com/square/okhttp/issues/95), but you still can do something like this:

        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(interceptor)
                .readTimeout(15, TimeUnit.SECONDS)
                .writeTimeout(15, TimeUnit.SECONDS)
                .connectTimeout(15, TimeUnit.SECONDS)
                .dns(hostname -> Single.fromCallable(
                        () -> Arrays.asList(InetAddress.getAllByName(hostname))
                ).timeout(15, TimeUnit.SECONDS)
                        .subscribeOn(Schedulers.io())
                        .observeOn(Schedulers.computation())
                        .onErrorReturnItem(new ArrayList<>())
                        .blockingGet())
                .build();

edited Jan 30 '19 at 16:14

answered Nov 01 '18 at 19:57

Dmitry Zenovich

184
9

Thanks for this. Quick question, why observeOn(Schedulers.computation())? Do you think subscribeOn(Schedulers.trampoline()) with no observeOn might make sense? Or even no subscribeOn or observeOn whatsoever – Aleksander Niedziolko Apr 07 '21 at 14:55
The `observeOn` could be irrelevant. But the `subscribeOn` is very important. Without it, `timeout` would not work correctly. When not using a `subscribeOn`, when a `timeout` happens it will try to call `onError` on the subscriber, but instead of releasing the latch holding the `blockingGet`, it will get blocked because the upstream stuff is already running on the same thread. In those cases you get the worst of both worlds: the computation will take as long as the upstream operators take, but once they finished the timeout exception will be thrown and the result will be lost. – Cristian Aug 11 '23 at 19:28

score 0 · Answer 2 · answered Dec 07 '22 at 07:03

Kotlin

class CustomDns : Dns {
        override fun lookup(hostname: String): List<InetAddress> {
            return Single.fromCallable {
                InetAddress.getAllByName(hostname)
            }.timeout(15, TimeUnit.SECONDS)
                .subscribeOn(Schedulers.io())
                .observeOn(Schedulers.computation())
                .onErrorReturnItem(arrayOf())
                .blockingGet().toList()
        }
    }


OkHttpClient.Builder()
            .connectTimeout(15, TimeUnit.SECONDS)
            .readTimeout(30, TimeUnit.SECONDS)
            .writeTimeout(15, TimeUnit.SECONDS)
            .dns(CustomDns())
            .build()

Okhttp3 set timeout is useless

2 Answers2

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