如何在 C# 中创建线程安全的列表池？

Question

Old title: Is an array of lists thread safe in C#?
I try to use a pool of lists for parallel processing. I create lists in an array and then use a ConcurrentBag of integers to allocate them to threads. Since the entire code is quite long I made an excerpt. In the below example each thread would need 5 lists of object x.

int maxThreads = 64;
ConcurrentBag<int> pool = new ConcurrentBag<int>();
// Populate ConcurrentBag with values 0 through 63
for (int i = 0; i <= maxThreads - 1; i++)
{
     pool.Add(i);           
}
List<x>[,] ABCList = new List<x>[maxThreads, 5];
Parallel.ForEach(zList,
new ParallelOptions { MaxDegreeOfParallelism = maxThreads },
p =>
{
     while (!pool.TryTake(out slot));
     // Do something here with ABCList[slot, 1....5]
     // Example: ABCList[slot, 1].[1].Field1 = 2;
     // Example: ABCList[slot, 1].[1].Field2 = "abc";
     pool.Add(slot);
});

So this runs without an error or any warnings. However inside parallel processing it sometimes fails to update values in ABCList[slot, 1....5]. By sometimes I mean 2-5 cases out of 1000. When I check in debug mode I can't reproduce the symptom. When I press F11 the list values are updated.
Please consider that I'm a hobby programmer and I may do something obviously wrong here. Any ideas how to do this correctly?
EDIT
Based on the suggestion of Peter I rewrote like this:

int maxThreads = 64;
ConcurrentBag<int> pool = new ConcurrentBag<int>();
ConcurrentDictionary <int, List<x>[]> ABCList = new ConcurrentDictionary<int, List<x>[]>();
// Initialize ConcurrentDictionary
for (int i = 0; i < maxThreads; i++)
{
     pool.Add(i);
     ABCList[i] = new List<x>[5];
     for (int w = 0; w <= 4; w++)
     {
          ABCList[i][w] = templateABCList[w].ConvertAll(p => p);
     }
}
Parallel.ForEach(zList,
new ParallelOptions { MaxDegreeOfParallelism = maxThreads },
p =>
{
     while (!pool.TryTake(out slot));
     // Do something here with ABCList[slot][1...5]
     // Example: ABCList[slot][1][1].Field1 = 2;
     // Example: ABCList[slot][1][1].Field2 = "abc";
     pool.Add(slot);
});

The problem still exists. The list fails to update in some cases. What do I do wrong?

Answer 1

You can Use System.Collections.Concurrent Name Space for Thread Safe Collections, and you can Use ConcurrentBag Class to Create Object(List) Pool

if you want Any list in pool is Thread safe , you can Use

var threadSafeArrayList = ArrayList.Synchronized(new ArrayList());

For Create each List Object