Hands-On Design Patterns and Best Practices with Julia

Understanding the performance impact of exception handling

There is actually a performance overhead to use a try-catch block. In particular, if the application is doing something in a tight loop, it would be a bad idea to catch exceptions inside the loop. To understand the impact, let's try a simple example.

Consider the following code that simply calculates the sum of the square root of every number in an array:

function sum_of_sqrt1(xs)    total = zero(eltype(xs))    for i in eachindex(xs)        total += sqrt(xs[i])    end    return totalend

Knowing that sqrt may throw DomainError for negative numbers, our first attempt may be to catch such exceptions inside the loop:

function sum_of_sqrt2(xs)    total = zero(eltype(xs))    for i in eachindex(xs)        try total += ...