WebSphere 8.5.5.2迁移至8.5.5.11（JDK8）：驱动兼容性及高负载问题咨询

Hey there! Let's dig into your WebSphere migration and database driver questions—since you're moving to 8.5.5.11 with JDK 8, compatibility and high-load stability are key. Here's a breakdown tailored to your setup:

DB2: db2jcc.jar, db2jcc_license_cu.jar, db2jcc_license_cisuz.jar #

• The DB2 JCC drivers officially support JDK 8 starting with version 3.72. Since you can already connect successfully, your current drivers likely have basic compatibility with JDK 8. But if these are the same drivers you used with WebSphere 8.5.5.2 (which is older), they might be a legacy version with unpatched bugs.
• Recommendation: Upgrade to the latest JCC driver matching your DB2 server version (e.g., DB2 10.5 or 11.1's JCC drivers, both fully JDK 8-compliant). This will fix potential high-load issues like connection pool leaks or performance bottlenecks that old drivers might have.

Oracle: ojdbc14.jar #

• This is a critical one: ojdbc14.jar was built for JDK 1.4, and it does NOT support JDK 8 properly. The fact that it connects now is just JDK 8's backward compatibility masking underlying issues. Under high load, or when using any JDK 8 features (even indirectly), you'll run into hard-to-debug errors—think NoSuchMethodError, class loading failures, or even silent data inconsistencies.
• Must Replace: Switch to ojdbc7.jar (supports JDK 7/8) or ojdbc8.jar (optimized for JDK 8). Make sure the driver version matches your Oracle database version (e.g., ojdbc8 pairs best with Oracle 12c+).

Sybase: jconn4.jar #

• jconn4.jar was designed for JDK 6 and above, so it does support JDK 8. That said, not all jconn4 versions are equal—older builds for Sybase ASE 15.5 or earlier might have minor compatibility quirks under heavy concurrency.
• Recommendation: Verify your jconn4 version. If it's outdated, upgrade to the latest release for your Sybase ASE version (15.7 or 16.0). This will ensure smoother connection handling under high load.

Even though your connections work now, high traffic can expose hidden issues:

• Incompatible drivers (like ojdbc14): Legacy drivers often don't handle JDK 8's thread model or concurrency optimizations well, leading to connection leaks, timeouts, or deadlocks under load.
• Unpatched bugs in old drivers: Older DB2 JCC builds had known issues with connection pool recycling, and outdated jconn4 versions could have transaction handling glitches when many connections are active.
• Don't forget to tune WebSphere's connection pool settings (max connections, timeout values) to match your driver's capabilities and application workload—this goes a long way in preventing high-load connection problems.

内容的提问来源于stack exchange，提问作者springbootlearner