We've been making some strides towards Julia being easier to embed lately. Calling exit in jl_init is definitely no good – that should be changed to return an error code that can be trapped and handled appropriately. It would be helpful to know what error message you're getting.
The use of global state for the Julia interpreter is unlikely to go away, although it is certainly possible. It may, however, be easier to have multiple independent Julia interpreters in a single process with separate Julia Core/Base/Main modules. If the interpreters are going to be in different threads, there would have to be locks around access to mutable global structures, but that might be ok. Unlike, say Python, there's no interpreter, so there would be no GIL – once code is generated, it can freely execute without different threads blocking each other. That would actually be a rather interesting project. You also have to be aware that many of the libraries that Julia uses are not threadsafe. Regarding startup time, we do have the ability to load a pre-compiled system image from a .so file these days, which takes about 0.3 seconds on my system – that's not super fast, but it's ok. If you're giving the wrong path to Julia, it's possible that it's not finding a system image, then again, if it's not finding the system image, it's probably not JITing anything. Embedded Julia code may still JIT. On Sun, Mar 23, 2014 at 7:16 AM, Dibyendu Majumdar <mob...@majumdar.org.uk>wrote: > Hi, > > I am working on a financial app where I would very much like to use Julia. > I am currently using Lua as an embedded scripting language, but Lua doesn't > perform very well with numeric computing. I have tried Luajit but no luck > as Luajit doesn't optimise very well when called as callbacks from C++. > > Julia seems to be the language I was looking for. I tried a small > experiment of calling Julia from C++ and noticed a few things: > > 1. The jl_init() function called exit() because it did not like the path > to Julia home directory. > 2. There doesn't seem to be a way to control instances of Julia - it seems > to rely on global state management. There seems to be an assumption that > there is only one global Julia environment in an app. > 3. The startup appears to take time. > > These are kind of show stopper issues for my use case so I was wondering > if: > > a) There are plans to make Julia more embeddable ... or is that a non-goal > or low priority? > b) How hard is it to change Julia to encapsulate all state in a Struct of > some sort? Is this impossible - or can it be done? > > One other thing that I have been trying to work out is whether Julia JITs > code when it is called in an embedded manner - this point doesn't seem to > be covered in the Julia documentation. > > Thanks and Regards > > Dibyendu > >
