C#•2y ago

✅ How to improve Parallel.ForEachAsync usage?

private async Task<ConcurrentDictionary<string, string>> GetIpAddresses( HashSet<string> deviceIds )     
{
    var devicesIpAddresses = new ConcurrentDictionary<string, string>();
                                                                                                         
    await Parallel.ForEachAsync(deviceIds, async (deviceId, _) => 
    {
        var archiveQuery = await _archiveClient
            .Query( new QueryArguments
            {
                DeviceIDs = new HashSet<string> {deviceId},
                Order = OrderType.Desc,
                EventNames = new() {"nc100k:connected", "nc60k:connected", "nc8k:connected"},
                Pagination = new() {PageSize = 1} 
            } )                                                                                          
            .Unwrap();                                                                                   
                                                                                                         
        var ip = archiveQuery.Items
            .Select(verbalizedEvent => verbalizedEvent.Items
                .FirstOrDefault(item => item.Type == "endpoint" )?.Title)                              
            .FirstOrDefault() ?? "";                                                                     
                                                                                                         
        devicesIpAddresses[deviceId] = ip;                                                             
    } );                                                                                                 
                                                                                                         
    return devicesIpAddresses;                                                                           
}

private async Task<ConcurrentDictionary<string, string>> GetIpAddresses( HashSet<string> deviceIds )     
{
    var devicesIpAddresses = new ConcurrentDictionary<string, string>();
                                                                                                         
    await Parallel.ForEachAsync(deviceIds, async (deviceId, _) => 
    {
        var archiveQuery = await _archiveClient
            .Query( new QueryArguments
            {
                DeviceIDs = new HashSet<string> {deviceId},
                Order = OrderType.Desc,
                EventNames = new() {"nc100k:connected", "nc60k:connected", "nc8k:connected"},
                Pagination = new() {PageSize = 1} 
            } )                                                                                          
            .Unwrap();                                                                                   
                                                                                                         
        var ip = archiveQuery.Items
            .Select(verbalizedEvent => verbalizedEvent.Items
                .FirstOrDefault(item => item.Type == "endpoint" )?.Title)                              
            .FirstOrDefault() ?? "";                                                                     
                                                                                                         
        devicesIpAddresses[deviceId] = ip;                                                             
    } );                                                                                                 
                                                                                                         
    return devicesIpAddresses;                                                                           
}

6 Replies

SWEETPONYOP•2y ago

everything works for me, but I'm not sure if it's all well written

JakenVeina•2y ago

I question the value of using parallelism here at all I question the idea of returning a ConcurrentDictionary as opposed to an IDictionary or just Dictionary otherwise, seems fine

anita•2y ago

As with your last question, this does not look like CPU Bound work to me, so you shouldn’t be the Parallel class.

SWEETPONYOP•2y ago

I tried simple foreach and parallel version second one was x2 faster 53 ms vs 106 Hmm

JakenVeina•2y ago

measured how? what did the foreach version look like?

SWEETPONYOP•2y ago

1. 
var timeWatch = new StopWatch();
timeWatch.Start();
foreach(var deviceIdin deviceIds)
{
      await blah blah.. 
}
timeWatch.Stop();
2.
var timeWatch2 = new StopWatch();
timeWatch2.Start();
await Parallel.ForEachAsync(deviceIds, async (deviceId, _) =>
{
     await blah blah..
}
timeWatch2.Stop();

1. 
var timeWatch = new StopWatch();
timeWatch.Start();
foreach(var deviceIdin deviceIds)
{
      await blah blah.. 
}
timeWatch.Stop();
2.
var timeWatch2 = new StopWatch();
timeWatch2.Start();
await Parallel.ForEachAsync(deviceIds, async (deviceId, _) =>
{
     await blah blah..
}
timeWatch2.Stop();

and the second one is faster ..

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✅ How to improve Parallel.ForEachAsync usage?