Explain how garbage collection works in Java and how it affects performance. Consider the differences between various garbage collectors (e.g., G1, CMS). What are the implications of garbage collection on multi-threaded applications? Provide examples of performance impacts you might observe.

**LeetCode #3 - Longest Substring Without Repeating Characters**\nGiven a string s, find the length of the longest substring without repeating characters. This problem helps in understanding the sliding window technique. It is commonly used for string manipulation problems.\n\n**Function Signature:** `def length_of_longest_substring(s: str) -> int:`\n\n**Example 1:**\nInput: `s = 'abcabcbb'`\nOutput: `3`\nExplanation: The answer is 'abc', with the length of 3.\n\n**Example 2:**\nInput: `s = 'bbbbb'`\nOutput: `1`\nExplanation: The answer is 'b', with the length of 1.\n\n**Constraints:**\n- 0 <= s.length <= 5 * 10^4\n- s consists of English letters, digits, symbols, and spaces.

**Design a Distributed Key-Value Store**\nYou are tasked with designing a distributed key-value store that needs to handle massive amounts of data and provide high availability and fault tolerance. Think about sharding, replication, consistency, and partitioning strategies. How would you ensure that data remains reliable and performant as the scale increases?\n\n**Considerations:**\n- Client interactions and API design\n- Data consistency models (strong vs eventual)\n- Error handling and recovery mechanisms