[SOLVED] How to resolve the error code 503 and 429 while reading all locations of all accounts using Google My Business Information API in Java

How to resolve the error code 503 and 429 while reading all locations of all accounts using Google My Business Information API in Java

I am going to retrieve all the locations of all accounts using Google My Business Business Information API, documented Google Business Profile APIs. I try to write the simplified version of my code below: Suppose mybusinessaccountLocations variable is the return type of following function and takes care of authentication and initialising the API.

MyBusinessBusinessInformation mybusinessaccountLocations = initializeMyBusiness(Host);

I have defined a class named accountRecord and locationRecord for managing the related tables in my DB.

ExecutorService ex = Executors.newFixedThreadPool(10);

    for (accountRecord rec : accountsList) {
        List<locationRecord> LocationsList = Collections.synchronizedList(new ArrayList<>());

        ex.execute(new Runnable() {
            @Override
            public void run() {
                String readMask = "storeCode,regularHours,name,languageCode,title,phoneNumbers,categories,storefrontAddress,websiteUri,regularHours,specialHours,serviceArea,labels,adWordsLocationExtensions,latlng,openInfo,metadata,profile,relationshipData,moreHours";

                List<Location> locations = Collections.synchronizedList(new ArrayList<>());
        
                String accountName = rec.getName();


                try {

                    MyBusinessBusinessInformation.Accounts.Locations.List locationsList = mybusinessaccountLocations
                            .accounts().locations().list(accountName).setReadMask(readMask);
                    ListLocationsResponse Response = locationsList.execute();
                    locations = Response.getLocations();
                    System.out.println("Response Size ="+ Response.size());
                    while (Response.getNextPageToken() != null && Response != null && !Response.isEmpty()) {
                        locationsList.setPageToken(Response.getNextPageToken());
                        Response = locationsList.execute();
                        if (Response != null && Response.getLocations() != null) {
                            locations.addAll(Response.getLocations());
                         
                        }  
                    }

                }  
                catch (Throwable t) {
                    throw new RuntimeException("\n\n Throwable occurred: " + t.getMessage(), t);
                }


            
                if (locations != null && !locations.isEmpty()) {
                  // processing the locations and saving in DB
                    .
                    .
                    .

                }

            }
        });


    }

    ex.shutdown();

    while (!ex.isTerminated()) {
    }

Since, I am using ExecutorService , sometimes it exceeds the time_limit defined by google (Quota), or there are server_side errors such as

 {
  "code" : 503,
  "errors" : [ {
    "domain" : "global",
    "message" : "The service is currently unavailable.",
    "reason" : "backendError"
  } ],
  "message" : "The service is currently unavailable.",
  "status" : "UNAVAILABLE"
}

I need the code wait some milliseconds up until there is no more such errors and retry the exact request without skipping any pagination or account. I tried to use AtomicInteger
and

synchronized(i) {
                         
        if( i.getAndIncrement() >= 50 ) {

            Thread.sleep(20000);
            i.set(0);
            }
        }

However, this is not a very efficient method, I have heard Exponential Backoff would be more efficient, but I do not know how to implement. I would appreciate any help.

Solution