System Performance and Stability Failures
#1 Server overload & crash:
The sudden surge in concurrent requests (or simultaneous, identical actions like everyone submitting a form at once) can quickly overwhelm the server. This results in system failures (crashes) or timeouts/outages (500 or 503 errors), stopping testing for everyone.
#2 Severe performance degradation:
While the system may not crash, the load can cause extremely slow load times or high latency (delayed response times). This makes the application unusable for testing and invalidates any performance data collected.
#3 Database Bottlenecks:
The database is often the first component to fail under heavy load. Many concurrent read/write operations can cause unoptimized queries to take too long, leading to a backlog of requests and a system slowdown or crash.
#4 Resource such as RAM Exhaustion: The server may run out of key resources like available memory (RAM) or the limit on the number of entry processes (simultaneous scripts) it can handle.
User/Client side Technical Issues
#1 Unstable internet connectivity issues: An unstable or slow internet connection for individual users can lead to disconnections, loss of progress, or failure to load test pages.
#2 Browser/Device compatibility:
The testing platform may not be compatible with all the operating systems, browsers, or device types (e.g., older laptops or different mobile phones) the users are using, creating a barrier to entry.
#3 Client side Technical flaws:
A user's device might have hardware or software issues, like low RAM, an incompatible operating system, or a slow CPU, which can prevent the application from running smoothly for them.
#4 Cache/Session Conflicts: With many users logging in and performing actions, issues like improper session handling or cache conflicts on the user's end can lead to incorrect data or log-in errors.
Data and Test Environment Issues
#1 Data Conflicts/Contentions:
If multiple testers are accessing and trying to modify the same test data record simultaneously, it can lead to locks, errors, or data corruption that stops the test. This is especially true for simultaneous users initiating identical, critical actions (e.g., reserving the last item).
#2 Unstable Test Environment: If the dedicated test environment is unstable, constantly updated, or being shared with other development activities, it can be unpredictable and lead to flaky tests (intermittent pass/fail results) that can't be reliably completed or analysed.
#3 Setup and Login Failures: The sheer scale of users logging in at once can expose weaknesses in the login process or user provisioning system, causing many testers to be unable to start.