Npgsql LISTEN Thread Crashing Server - multithreading

Question

I have a long running PostgreSQL function. For simplicity, something like this:
CREATE FUNCTION pg_function()
RETURNS void
AS
$$
BEGIN
PERFORM pg_notify('channel1', 'pg_function() started.');
PERFORM pg_sleep(5);------PERFORM task1();-----------------------------------------
PERFORM pg_notify('channel1', 'Task1 payload.');
PERFORM pg_sleep(5);------PERFORM task2();-----------------------------------------
PERFORM pg_notify('channel1', 'Task2 payload.');
PERFORM pg_sleep(5);------PERFORM task3();-----------------------------------------
PERFORM pg_notify('channel1', 'Task3 payload.');
PERFORM pg_notify('channel1', 'pg_function() completed.');
END;
$$
LANGUAGE "plpgsql";
On C#, I have:
public bool listening;
public void PgFunction()
{
this.listening = true;
ThreadStart listenerStart = delegate
{
using (NpgsqlConnection connection = new NpgsqlConnection(this.connectionString))
{
connection.Open();
connection.Notification += Listen;
using (NpgsqlCommand listenChannel1 = new NpgsqlCommand("LISTEN channel1;", connection))
{
listenChannel1.ExecuteNonQuery();
}
while (this.listening)
{
using (NpgsqlCommand pollingCommand = new NpgsqlCommand("SELECT 0;", connection))
{
pollingCommand.ExecuteNonQuery();
}
Thread.Sleep(5000);
}
}
};
Thread listenerThread = new Thread(listenerStart) { IsBackground = false };
listenerThread.Start();
ThreadStart pgFunctionThreadStart = () => ExecuteNonQuery(new NpgsqlCommand("SELECT pg_function();"));
pgFunctionThreadStart += () =>
{
Thread.Sleep(5000);
this.listening = false;
};
Thread pgFunctionThread = new Thread(pgFunctionThreadStart) { IsBackground = true };
pgFunctionThread.Start();
}
private void Listen(object sender, NpgsqlNotificationEventArgs e)
{
string payload = e.AdditionalInformation;
//SignalR stuff here
}
When I run the program debugging, this code works okay. But when it is tested on IIS server or browsed with Visual Studio 2013 integrated IIS, the application crashes. Since I have very little knowledge of tasks and threads in C#, I would like to know what I am doing wrong here? Please advise.
Edit
Upon debugging it again, I came with a NpgsqlException, which happens to happen once in a while:
Additional information: Cannot write to a BufferedStream while the read buffer is not empty if
the underlying stream is not seekable. Ensure that the stream underlying this BufferedStream
can seek or avoid interleaving read and write operations on this BufferedStream.