IntelliJ Copilot Bug: Impact on Developer Productivity & Performance

Developer frustrated by a Copilot error in IntelliJ

Copilot's IntelliJ Threading Bug: A Hiccup in Developer Productivity

In the fast-paced world of software development, tools like GitHub Copilot are designed to enhance efficiency and boost developer productivity. However, even the most advanced AI assistants can encounter technical glitches that disrupt workflow. A recent discussion on GitHub's community forum, initiated by user @tomerc, highlights a recurring exception faced by developers using Copilot within IntelliJ, posing a direct challenge to how we might measure performance of software developers when their essential tools are faltering.

The Recurring Exception: An EDT Threading Issue

The core of the problem lies in a RuntimeExceptionWithAttachments that frequently appears when Copilot is active in IntelliJ. The error message, "Access is allowed from Event Dispatch Thread (EDT) only," points to a classic threading issue common in Java Swing and IntelliJ Platform applications. Essentially, the Event Dispatch Thread (EDT) is responsible for all UI-related updates and interactions to maintain thread safety and responsiveness. The exception indicates that Copilot is attempting to access or modify UI components from a background thread, rather than the dedicated EDT, leading to instability and crashes.

This type of error, while technical, has significant implications for daily development work. When a tool meant to accelerate coding frequently throws exceptions, it forces developers to pause, restart, or troubleshoot, directly impeding their flow. This disruption makes it harder to maintain consistent output and, consequently, complicates efforts to accurately measure performance of software developers based on their coding velocity or task completion rates.

The Stack Trace: What the Error Reveals

The provided stack trace offers a detailed look into where the issue originates within Copilot's integration:

com.intellij.openapi.diagnostic.RuntimeExceptionWithAttachments: Access is allowed from Event Dispatch Thread (EDT) only; If you access or modify model on EDT consider wrapping your code in WriteIntentReadAction or ReadAction; see https://jb.gg/ij-platform-threading for details Current thread: Thread[#188,ApplicationImpl pooled thread 53,4,main] 873670901 (EventQueue.isDispatchThread()=false) SystemEventQueueThread: Thread[#37,AWT-EventQueue-0,10,main] 1055107926 at com.intellij.util.concurrency.ThreadingAssertions.createThreadAccessException(ThreadingAssertions.java:258) at com.intellij.util.concurrency.ThreadingAssertions.softAssertEventDispatchThread(ThreadingAssertions.java:90) at com.intellij.openapi.wm.impl.ToolWindowImpl.createContentIfNeeded(ToolWindowImpl.kt:731) at com.intellij.openapi.wm.impl.ToolWindowImpl.getContentManager(ToolWindowImpl.kt:590) at com.github.copilot.chat.window.CopilotChatToolWindow.currentContent(CopilotChatToolWindow.kt:359) at com.github.copilot.chat.window.CopilotChatToolWindow.updateUi(CopilotChatToolWindow.kt:323) at com.github.copilot.chat.window.CopilotChatToolWindow.subscribeToPreconditions$lambda$5(CopilotChatToolWindow.kt:234) at com.github.copilot.chat.precondition.PreconditionsService.executeJobsAsync$lambda$3(ChatPreconditionsService.kt:146) at com.intellij.openapi.application.impl.ApplicationImpl$4.run(ApplicationImpl.java:333) at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:545) at com.intellij.util.concurrency.ContextCallable.lambda$call$1(ContextCallable.java:86) at com.intellij.concurrency.ThreadContext.installThreadContext(threadContext.kt:305) at com.intellij.util.concurrency.ContextCallable.lambda$call$2(ContextCallable.java:83) at com.intellij.util.concurrency.ContextCallable.call(ContextCallable.java:96) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:328) at com.intellij.util.concurrency.ChildContext$runInChildContext$1.invoke(propagation.kt:170) at com.intellij.util.concurrency.ChildContext$runInChildContext$1.invoke(propagation.kt:170) at com.intellij.util.concurrency.ChildContext.runInChildContext(propagation.kt:176) at com.intellij.util.concurrency.ChildContext.runInChildContext(propagation.kt:170) at com.intellij.util.concurrency.ContextRunnable.lambda$run$0(ContextRunnable.java:26) at com.intellij.concurrency.ThreadContext.resetThreadContext(threadContext.kt:294) at com.intellij.util.concurrency.ContextRunnable.run(ContextRunnable.java:25) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614) at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:649) at java.base/java.lang.Thread.run(Thread.java:1474)

The stack trace clearly points to com.github.copilot.chat.window.CopilotChatToolWindow.updateUi and currentContent methods, indicating that the Copilot chat window's UI update logic is attempting to modify UI elements off the EDT. This is a critical bug that needs addressing to ensure the stability of the plugin.

GitHub's Acknowledgment and Next Steps

A prompt reply from github-actions confirmed that the feedback was received and would be reviewed by product teams. While no immediate solution or workaround was provided, the response assured the community that such input is invaluable for product improvements. This highlights the importance of community discussions in identifying critical issues that impact developer workflow and, by extension, the overall effectiveness of engineering teams.

The Broader Impact on Engineering Analytics

Beyond the immediate frustration, recurring bugs in core development tools can skew any attempt at objective engineering analytics. If developers are constantly battling tool-related issues, their true productivity and efficiency are masked. Reliable tools are foundational for accurate performance metrics, and when they falter, the data collected on developer activity might not reflect their actual potential or the effectiveness of their work processes. For teams focusing on OKRs for engineering teams, stable tooling is a prerequisite for achieving targets and measuring progress accurately.

This incident underscores the continuous challenge of integrating complex AI tools into existing IDEs. Ensuring seamless, thread-safe operation is paramount for maintaining developer trust and maximizing the benefits of AI assistance. The community eagerly awaits a resolution to this bug, hoping for a smoother, more reliable Copilot experience in IntelliJ.

Developers experiencing similar issues are encouraged to upvote the discussion and add further details, use cases, or screenshots to help the GitHub team prioritize and resolve this critical bug.