[Linux] 編譯 Google Protocol Buffer 時不要用 make -j 平行編譯
前一陣子幫專案用 make -j 的方式，執行平行編譯，加快編譯的速度，
不過最近在加上 Google Protocol Buffer 的編譯之後，
卻發現常常在編譯到 Google Protocol Buffer 時，編譯速度突然變得非常的慢，
甚至會有機器好像整台停下來的狀況…
研究了一下，原來是記憶體用量的問題…
使用 make -j 時，只要有 make 的動作，就會再多跑出一個 process 來編譯，
以 Google Protocol Buffer 來說，似乎它裡面會去 make 非常多的東西，
導致有非常多的 process 都在執行 make，把記憶體都吃光光，
最後記憶體沒了之後，就開始吃 SWAP，自然電腦速度就會變得超慢的了…
下面是用 make -j 編譯 Google Protocol Buffer，觀察記憶體的使用量～
可以看到原本還有剩 5GB，後來越來越少，最後只剩一百多 MB：
Fri Feb 17 17:23:33 CST 2017 total used free shared buffers cached Mem: 7.6G 2.6G 5.0G 2.5M 0B 2.1G -/+ buffers/cache: 567M 7.1G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:35 CST 2017 total used free shared buffers cached Mem: 7.6G 2.8G 4.9G 2.5M 0B 2.1G -/+ buffers/cache: 725M 6.9G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:38 CST 2017 total used free shared buffers cached Mem: 7.6G 3.5G 4.1G 2.5M 0B 2.1G -/+ buffers/cache: 1.4G 6.2G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:40 CST 2017 total used free shared buffers cached Mem: 7.6G 4.1G 3.5G 2.5M 0B 2.1G -/+ buffers/cache: 2.0G 5.6G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:43 CST 2017 total used free shared buffers cached Mem: 7.6G 4.7G 3.0G 2.5M 0B 2.1G -/+ buffers/cache: 2.6G 5.0G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:45 CST 2017 total used free shared buffers cached Mem: 7.6G 4.8G 2.9G 2.5M 0B 2.1G -/+ buffers/cache: 2.7G 4.9G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:48 CST 2017 total used free shared buffers cached Mem: 7.6G 5.1G 2.5G 2.5M 0B 2.1G -/+ buffers/cache: 3.1G 4.6G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:51 CST 2017 total used free shared buffers cached Mem: 7.6G 5.3G 2.3G 2.5M 0B 2.1G -/+ buffers/cache: 3.3G 4.4G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:54 CST 2017 total used free shared buffers cached Mem: 7.6G 5.5G 2.1G 2.5M 0B 2.1G -/+ buffers/cache: 3.5G 4.2G Swap: 7.9G 896M 7.0G Fri Feb 17 17:23:56 CST 2017 total used free shared buffers cached Mem: 7.6G 5.8G 1.9G 2.5M 0B 2.1G -/+ buffers/cache: 3.7G 3.9G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:00 CST 2017 total used free shared buffers cached Mem: 7.6G 6.1G 1.5G 2.5M 0B 2.1G -/+ buffers/cache: 4.0G 3.6G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:03 CST 2017 total used free shared buffers cached Mem: 7.6G 6.3G 1.4G 2.5M 0B 2.1G -/+ buffers/cache: 4.2G 3.4G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:06 CST 2017 total used free shared buffers cached Mem: 7.6G 6.6G 1.0G 2.5M 0B 2.1G -/+ buffers/cache: 4.5G 3.1G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:09 CST 2017 total used free shared buffers cached Mem: 7.6G 7.0G 703M 2.5M 0B 2.1G -/+ buffers/cache: 4.9G 2.8G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:12 CST 2017 total used free shared buffers cached Mem: 7.6G 7.2G 462M 2.5M 0B 2.1G -/+ buffers/cache: 5.1G 2.5G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:16 CST 2017 total used free shared buffers cached Mem: 7.6G 7.5G 158M 2.5M 0B 1.8G -/+ buffers/cache: 5.7G 2.0G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:21 CST 2017 total used free shared buffers cached Mem: 7.6G 7.5G 132M 2.5M 0B 1.4G -/+ buffers/cache: 6.1G 1.5G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:25 CST 2017 total used free shared buffers cached Mem: 7.6G 7.5G 110M 2.5M 0B 914M -/+ buffers/cache: 6.6G 1.0G Swap: 7.9G 896M 7.0G Fri Feb 17 17:24:28 CST 2017 total used free shared buffers cached Mem: 7.6G 7.5G 101M 2.5M 0B 554M -/+ buffers/cache: 7.0G 655M Swap: 7.9G 896M 7.0G
後來將編譯 Google Protocol Buffer 的部分時，
指定成 make -j 1 (也就是不多開新的 process)，就沒有這個問題了～
(本頁面已被瀏覽過 293 次)