Explain the concept of concurrency in Java. How does Java's concurrency model work and what constructs does it provide for thread management? Discuss how to avoid issues such as deadlocks and race conditions.

LeetCode #3 - Longest Substring Without Repeating Characters\nGiven a string, find the length of the longest substring without repeating characters. For example, in the string 'abcabcbb', the answer is 3, with the substring being 'abc'.\n\n### Problem Statement\n```python\ndef length_of_longest_substring(s: str) -> int:\n```\n### Example 1\n**Input:** 'abcabcbb' \n**Output:** 3 \n**Explanation:** The longest substring is 'abc', which has length 3.\n\n### Example 2\n**Input:** 'bbbbb' \n**Output:** 1 \n**Explanation:** The longest substring is 'b', with length 1.\n\n### Constraints\n* 0 <= s.length <= 1000\n* s consists of English letters, digits, symbols and spaces.

Design a URL shortening service like Bitly. Consider functionality such as creating a short URL, redirecting to the original URL, and tracking analytics. Describe your approach to managing these features and which key components would be included in the architecture.