Reason opt.lg_dirty_mult is not writable?

Jason Evans jasone at
Wed Jan 21 13:32:39 PST 2015

On Jan 21, 2015, at 1:25 PM, D'Alessandro, Luke K <ldalessa at> wrote:
>> On Jan 21, 2015, at 4:10 PM, Jason Evans <jasone at> wrote:
>> Can you instead set malloc_conf (with appropriate mangling) to "lg_dirty_mult:-1”?  
> Ah, maybe? I didn’t realize that we could mangle those up front, the opt code can be pretty opaque :-) That would be good enough for my purposes. So if my configuration normally generates the symbol as “prefix_je_opt_lg_dirty_mult”, then can I use that fully mangled name?

You can use PREFIX_MALLOC_CONF=lg_dirty_mult:-1 in the environment, or you can use prefix_malloc_conf = "lg_dirty_mult:-1" in C code.  There should be a distinct *MALLOC_CONF and *malloc_conf for each version of jemalloc you link into your application.

> As a side note, we run into some symbols that aren’t properly mangled to link against two jemalloc instances. At some point (soon) we’ll submit an upstream patch to mangle them.

I just integrated a patch for this today (


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