Merge pull request #88 from JuliaData/jps/approx_size-opt

Optimizations to `approx_size` and `ensure_memory_reserved`

src/MemPool.jl

@@ -63,8 +63,12 @@ include("datastore.jl")
 
 Returns the size of `d` in bytes used for accounting in MemPool datastore.
 """
-function approx_size(@nospecialize(d))
-    Base.summarysize(d) # note: this is accurate but expensive
+function approx_size(d::T) where T
+    if Base.datatype_pointerfree(T)
+        return sizeof(d)
+    else
+        Base.summarysize(d) # note: this is accurate but expensive
+    end
 end
 
 function approx_size(d::Union{Base.BitInteger, Float16, Float32, Float64})

src/datastore.jl

@@ -385,7 +385,7 @@ const MEM_RESERVE_LOCK = Threads.ReentrantLock()
 const MEM_RESERVE_SWEEPS = Ref{Int}(3)
 
 """
-When called, ensures that at least `MEM_RESERVED[] + size` bytes are available
+When called, ensures that at least `MEM_RESERVED[]` bytes are available
 to the OS. If there is not enough memory available, then a variety of calls to
 the GC are performed to free up memory until either the reservation limit is
 satisfied, or `max_sweeps` number of cycles have elapsed.
@@ -396,15 +396,15 @@ function ensure_memory_reserved(size::Integer=0; max_sweeps::Integer=MEM_RESERVE
     max_sweeps == 0 && return
 
     # Do a quick (cached) check, to optimize for many calls to this function when memory isn't tight
-    if Int(storage_available(CPURAMResource())) - size >= MEM_RESERVED[]
+    if Int(storage_available(CPURAMResource())) >= MEM_RESERVED[]
         return
     end
 
     # Check whether the OS is running tight on memory
     sweep_ctr = 0
     while true
         with(QUERY_MEM_OVERRIDE => true) do
-            Int(storage_available(CPURAMResource())) - size < MEM_RESERVED[]
+            Int(storage_available(CPURAMResource())) < MEM_RESERVED[]
         end || break
 
         # We need more memory! Let's encourage the GC to clear some memory...
@@ -425,7 +425,7 @@ function ensure_memory_reserved(size::Integer=0; max_sweeps::Integer=MEM_RESERVE
         yield()
 
         # Wait for send queue to clear
-        while SEND_QUEUE.processing
+        while SEND_QUEUE.processing || !isempty(SEND_QUEUE.queue)
             yield()
         end
 

src/storage.jl

@@ -163,12 +163,11 @@ struct CPURAMResource <: StorageResource end
 if Sys.islinux()
 function free_memory()
     open("/proc/meminfo", "r") do io
-        # skip first 2 lines
-        readline(io)
-        readline(io)
-        line = readline(io)
-        free = match(r"MemAvailable:\s*([0-9]*)\s.*", line).captures[1]
-        parse(UInt64, free) * 1024
+        # TODO: Cache in TLS
+        buf = zeros(UInt8, 128)
+        readbytes!(io, buf)
+        free = match(r"MemAvailable:\s*([0-9]*)\s.*", String(buf)).captures[1]
+        return parse(UInt64, free) * 1024
     end
 end
 else