Go GC: Latency Problem Solved Rick Hudson Google Engineer GopherCon Denver July 8, 2015 Google Confidential and Proprietary My Codefendants: The Cambridge Runtime Gang https://upload.wikimedia.o #1 Barrier: GC Latency Google Confidential and Proprietary When is the best time to do a GC? When nobody is looking. Using camera to track eye movement When subject looks away do a GC. Recovering org/wiki/File:WIFI_icon.svg#globalusage Google Confidential and Proprietary Or Trade Throughput for Reduced GC Latency Google Confidential and Proprietary Latency Nanosecond 1: Grace Hopper Nanosecond

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1965 106.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1968 106.27 Garbage Collection in Julia . . . addprocs and pass -t/--threads as exeflags.CHAPTER 25. MULTI-THREADING 323 Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1913 105.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1916 105.27 Garbage Collection in Julia . . . control over worker threads use addprocs and pass -t/--threads as exeflags. Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1913 105.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1916 105.27 Garbage Collection in Julia . . . control over worker threads use addprocs and pass -t/--threads as exeflags. Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1913 105.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1916 105.27 Garbage Collection in Julia . . . control over worker threads use addprocs and pass -t/--threads as exeflags. Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1606 101.24 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1618 101.25 Garbage Collection in Julia . . . control over worker threads use addprocs and pass -t/--threads as exeflags. Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1606 101.24 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1618 101.25 Garbage Collection in Julia . . . control over worker threads use addprocs and pass -t/--threads as exeflags. Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1963 106.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1966 106.27 Garbage Collection in Julia . . . addprocs and pass -t/--threads as exeflags.CHAPTER 25. MULTI-THREADING 323 Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1963 106.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1966 106.27 Garbage Collection in Julia . . . addprocs and pass -t/--threads as exeflags.CHAPTER 25. MULTI-THREADING 323 Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least

. . . . . . . . . . . . . . . . . . . . . . . . . . . 1963 106.26 Static analyzer annotations for GC correctness in C code . . . . . . . . . . . . . . . 1966 106.27 Garbage Collection in Julia . . . addprocs and pass -t/--threads as exeflags.CHAPTER 25. MULTI-THREADING 323 Multiple GC Threads The Garbage Collector (GC) can use multiple threads. The amount used is either half the number of com- pute worker threads or configured by either the --gcthreads command line argument or by using the JULIA_NUM_GC_THREADS environment variable. Julia 1.10 The --gcthreads command line argument requires at least