性能分析 #

@time sum(rand(10^6))

result = @timed sum(rand(10^6))
result.time
result.bytes
result.value

@elapsed sum(rand(10^6))

@allocated sum(rand(10^6))

using Profile

function slow_function(n)
    total = 0.0
    for i in 1:n
        total += sqrt(i)
    end
    return total
end

@profile slow_function(10^6)
Profile.print()

Profile.clear()

Profile.init(n=10^6, delay=0.001)

using Pkg
Pkg.add("ProfileViz")

using ProfileViz

@profview slow_function(10^6)

function allocate_test()
    x = [1, 2, 3, 4, 5]
    sum(x)
end

@allocated allocate_test()

@time allocate_test()

using Pkg
Pkg.add("MemoryProfiler")

using MemoryProfiler

@profile_memory allocate_test()

function unstable(x)
    if x > 0
        return x
    else
        return "negative"
    end
end

@code_warntype unstable(1)

@code_typed unstable(1)

@code_llvm unstable(1)

@code_native unstable(1)

using Pkg
Pkg.add("JET")

using JET

@report_opt unstable(1)

using JET

function buggy(x)
    if x > 0
        return x
    else
        return "error"
    end
end

@report_call buggy(1)

using Profile

function fibonacci(n)
    n <= 1 ? n : fibonacci(n-1) + fibonacci(n-2)
end

@profile fibonacci(30)
Profile.print()

function bad_sum(arr)
    total = 0
    for x in arr
        total += x
    end
    return total
end

function good_sum(arr)
    total = 0.0
    for x in arr
        total += x
    end
    return total
end

arr = rand(10^6)
@time bad_sum(arr)
@time good_sum(arr)

function check_type_stability(f, args...)
    code = @code_warntype f(args...)
    if occursin("Any", string(code))
        @warn "Type instability detected"
        return false
    end
    return true
end

check_type_stability(x -> x > 0 ? x : 0.0, 1)