Application.renderToString performance

[swolfod]

I am building an isomorphic app upon marty and I noticed that Application.renderToString is not performing well and can easily take hundreds of milliseconds for simple pages.

By investigating the source code I found out that it was because in the internal helper function waitForFetches in renderToString.js file calls React.renderToString for every cycle it hits detecting unfinished fetches. Even if there are absolutely no fetches the React.renderToString function is called at least twice, and for every fetch one more redundant rendering is made even if the data is already local. React.renderToString is VERY expensive and calling it multiple times in one request can easily eat up cpu power.

Now I understand that 0.10 is the final major release for marty. But I really hope this problem can be fixed and the redundant renderings can be removed.

Thanks for the great job!

[taion]

What do you propose? We use renderToString to figure out what fetches still need to be made - it's what walks down the component tree and ensures invocation of appropriate container methods.

[swolfod]

I will need to dig deeper into the code to come up with a possible solution. However, some tentative ideas may include either detecting pending fetches without calling renderToString, or call it only once for each node in the tree and keep the result.

[taion]

That's not quite right, BTW - renderToString kicks off a new cycle if it detects any new fetches have been made. Within any given render cycle, it won't end the cycle until all pending fetches have been resolved: https://github.com/martyjs/marty-lib/blob/v0.10.8/src/application/application.js#L167-L169

[swolfod]

Can the renderToString result be buffered during detecting so if there is no new fetches the buffered result can be used instead of making another call of renderToString?

Also, per my test, the diagnositics look like this when the render is finished:
[{ status: 'DONE',
storeId: 'testStore1',
fetchId: 'testfetch_0',
time: 84,
result: ... },
{ status: 'PENDING',
storeId: 'testStore1',
fetchId: 'testfetch_0',
time: 155,
result: ... }]

While all the data in testStore1 is local and do not require remote fetch. Why it is marked 'PENDING' and therefore triggers a new cycle?

[goldensunliu]

I am experiencing the same.
even odder is if when your local fetch returns the value false, it never gets to status: 'DONE' and retry as many cycles as marty allows.