Java8 CompletableFuture runAsync allof example 2019-06-23 03:12
In the previous blog Java8 CompletableFuture concurrence example we have learned how to use the method allof and supplyAsync of CompletableFuture to achieve concurrency. The problem is that the code is less readable when there are multiple CompletableFuture.
Consider the code in the previous blog
public static void main(String[] args) throws ExecutionException, InterruptedException {
long beginTime = System.currentTimeMillis();
String userName = "henry";
CompletableFuture<String> addressFuture = CompletableFuture.supplyAsync(() -> getAddress(userName));
CompletableFuture<String> companyNameFuture = CompletableFuture.supplyAsync(() -> getCompanyName(userName));
CompletableFuture<String> familyFuture = CompletableFuture.supplyAsync(() -> getFamilyInfo(userName));
CompletableFuture<String> allInfoFuture = CompletableFuture.allOf(addressFuture, companyNameFuture, familyFuture)
.thenApply(i -> {
String address = addressFuture.join();
String companyName = companyNameFuture.join();
String familyInfo = familyFuture.join();
return "userId:\t" + userName + " \r\n" + address + "\r\n" + companyName + "\r\n" + familyInfo;
});
String allInfo = allInfoFuture.get();
System.out.println(allInfo + "\r\ntime cost:" + (System.currentTimeMillis() - beginTime));
}
As the resources that require concurrent requests increase, the logic in the thenApply method will become very complicated. Using runAsync instead of supplyAsync, the code looks a lot cleaner.
public class CompletableFutureConcurrenceCodeFormatClient {
private static final Executor executor =
Executors.newFixedThreadPool(600, r -> {
Thread t = new Thread(r);
t.setDaemon(true);
return t;
});
public static void main(String[] args) throws ExecutionException, InterruptedException {
long beginTime = System.currentTimeMillis();
String userName = "henry";
UserInfo userInfo = new UserInfo();
CompletableFuture<Void> addressFuture = CompletableFuture.runAsync(() -> assembleAddress(userName, userInfo), executor);
CompletableFuture<Void> companyNameFuture = CompletableFuture.runAsync(() -> assembleCompany(userName, userInfo), executor);
CompletableFuture<Void> familyFuture = CompletableFuture.runAsync(() -> assembleFamilyInfo(userName, userInfo), executor);
CompletableFuture.allOf(addressFuture, companyNameFuture, familyFuture).join();
System.out.println("user info: " + userInfo + "\r\ntime cost:" + (System.currentTimeMillis() - beginTime));
}
private static void assembleCompany(String userName, UserInfo userInfo) {
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
userInfo.setCompanyName("my_company");
}
private static void assembleAddress(String userName, UserInfo userInfo) {
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
userInfo.setAddress("beijing");
}
private static void assembleFamilyInfo(String userName, UserInfo userInfo) {
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
userInfo.setFamilyInfo("wife and son");
}
}
Assemble attribute values in each concurrent method, rather than concurrently getting the attribute values before assembling.
EOF