How Accurate is Go's Claimed Nanosecond Time Precision?

Go's Time Precision: A Deeper Look

Go's time package claims to offer nanosecond precision, sparking questions about its accuracy. Python's well-documented time limitations raise concerns, as operating systems can pose challenges for precise timekeeping.

Implementation Details

time.Now() relies on a runtime function implemented in C. This function employs clock_gettime on Linux amd64, providing nanosecond resolution. On Windows, GetSystemTimeAsFileTime is used, also offering nanosecond granularity.

OS Dependence

Ultimately, the precision of Go's time depends on the OS. While the developers strive for high accuracy, some OSes may not be equally precise. For instance, in Go1.0.3, FreeBSD used less precise millisecond precision with gettimeofday, before being updated to clock_gettime.

Verification

To ensure accuracy, consult the runtime source code and OS documentation. By reviewing the assembly code and parameter values, you can verify the syscall used (e.g., clock_gettime for nanosecond precision).

Conclusion

While Go's time package aims to deliver nanosecond precision, the actual accuracy is OS-dependent. By understanding the implementation details and consulting OS documentation, you can assess the precision and reliability of the time functions for your specific use case.

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