Unable to get Async Retry Policy to work

Can someone see what I’m doing wrong below when implementing Async Retry Policy. This is causing a memory heap exception that crashes my IIS application pool.

1. I have an Async wrapper method using Dapper.QueryAsync<T>

    public static async Task<IEnumerable<T>> QueryAsyncWithRetry<T>(IDbConnection dbConnection, string sql, CommandType commandType, DynamicParameters paramList, int maxRetries = 3, int commandTimeout = 120)
        {
            try
            {
                //Need to verify retry when method is implemented
                var result = await (Task<IEnumerable<T>>)RetryPolicy.RetryForTimeoutAsync<T>(new Func<
                                                 string,
                                                 object,
                                                 IDbTransaction,
                                                 int?,
                                                 CommandType?,
                                                 Task<IEnumerable<T>>>(dbConnection.QueryAsync<T>),
                                                 maxRetries,
                                                 sql,
                                                 paramList,
                                                 null,
                                                 commandTimeout,
                                                 commandType
                                                 );
                return result;
            }
            catch (Exception ex)
            {
                _logger.Fatal(ex, $"DapperExtenions.QueryAsyncWithRetry<T> failed on {sql}");
                throw;
            }
        }

1. I create Policy using RetryAsync and ExecuteAsync.

    public static async Task<IEnumerable<T>> RetryForTimeoutAsync<T>(Delegate method, int maxRetries = 3, params object[] args)
        {
            var policy = Policy
                        .Handle<Exception>(ex => ExceptionMiner.FullMessageChain(ex).ToLower().Contains(timeout))
                        .Or<Exception>(ex => ExceptionMiner.FullMessageChain(ex).ToLower().Contains(deadlock))
                        .RetryAsync(maxRetries, (ex, retryCount) =>
                        {
                            _logger.Error(ex, $"Attempting retry {retryCount} of maxRetry {maxRetries} for timeout/deadlock on method {method.Method.Name}.  Parameter List Info: {GetPropertyValues(args)}");
                        });

            try
            {
                var result = await policy.ExecuteAsync(() => (Task<IEnumerable<T>>) method.DynamicInvoke(args));
                return result;
            }
            catch (Exception e)
            {
                //log the exception after maxRetries are reached or there is no retry exception being handled
                _logger.Fatal(e, $"RetryPolicy.Retry failed on method {method.Method.Name}. Parameter List Info: {GetPropertyValues(args)}");
                throw;
            }
        }

( EDITED: by @reisenberger to format code for readability. )

[duydle]

Thanks all for the response. At the moment, let’s close this ticket since I won’t be able spend too much time on this issue. For now we will not implement a retry on async calls. If I have availability, I will circle back and try to create a reproducible code sample and send your way. Thanks all for the quick responses.

[udlose]

@duydle -

1. what is the exact type of the exception? I’m not clear on what a “memory heap” exception is. What is the exception message?

2. I assume dbConnection.QueryAsync<T> returns a Task? Do you need to await that call?