high performance Nim - the first high performance language with full support for hot code- language with full support for hot code- reloading at runtime reloading at runtime by Viktor Kirilov 1 Me, myself the performant programming language landscape read: heavily biased C++ rant Nim compilation model hot code reloading usage & implementation ".dll" => assume .so/.dylib (platform-agnostic) demo comments shared libraries OR hot-patching: possible for decades - but not widely used usually quite intrusive (interfaces, constraints, complicated setup) in game engines: Unreal, others... hot-patching (with very

drives to form tiered memory for application processes. Its automatic memory scheduling redirects hot data to the high-speed DRAM and cold data to the low-speed media, expanding available memory and • Cold and hot tiering: In user mode, a memory access scan can be performed for a designated process. Cold and hot tiering policies are used to classify memory access results into hot and cold memory mechanism that does not affect user experience. User mode Kernel mode Accurate identification of hot and cold pages and in-service automatic swap Configurable process-level policy control Hardware Memory

the entire keyspace to find hot keys as well as # average sizes per key type. You can use -i 0.1 to sleep 0.1 sec # per 100 SCAN commands (not usually needed). [00.00%] Hot key 'counter:000000000002' found 00%] Hot key 'key:000000000001' found so far with counter 254 [00.00%] Hot key 'mylist' found so far with counter 107 [00.00%] Hot key 'key:000000000000' found so far with counter 254 [45.45%] Hot key found so far with counter 87 [45.45%] Hot key 'key:000000000002' found so far with counter 254 [45.45%] Hot key 'myset' found so far with counter 64 [45.45%] Hot key 'counter:000000000000' found so far

refined functions of memory initialization, memory control, statistics, heterogeneous memory, and hot swap, as well as more effective user control interfaces. A series of optimizations in hotspot lock Additionally, it enables perf nmi to perform more accurate performance analysis. 18. VM hot swap: CPU hot swap can be enabled in the ARM64 environment to obtain more flexible resource configurations ensure that services are not interrupted when rectifying kernel errors, the hot patch technology comes into play. However, hot patches can resolve only 20% of problems due to their limitations. For example

Others • An interface is added between TiDB and PD. When you use the information_schema �→ .TIDB_HOT_REGIONS_HISTORY system table, TiDB needs to use PD in the corre- sponding version. • TiDB Server, Access tier of the up- loaded objects (for ex- ample, Hot, Cool, Archive �→ ). If access �→ - �→ tier �→ is not set (the value is empty), the value is Hot by de- fault. To ensure that TiKV and BR use the access-tier | Access tier of the uploaded objects (for example, Hot, Cool, Archive). If access-tier is not set (the value is empty), the value is Hot by default. | BR sending credentials to TiKV By default

IstioMeetup 服务网格数据平面热升级技术分享 ServiceMesh Data-Plane Hot-Upgrade 阿里云服务网格团队 – 史泽寰 • 为什么需要服务网格数据面热升级 • 实现热升级 • 实践热升级 目录 Catalog 2 为什么需要服务网格数据面热升级 Why do we need Hot-Upgrade for ServiceMesh Data-Plane • 造成请求失败，影响业务质量 增加workload保持服务容量不变，应对大规模场景难以在扩容规模和操作便捷度上取 得令人满意的平衡 传统Sidecar升级方式的缺点 3 为什么需要服务网格数据面热升级 Why do we need Hot-Upgrade for ServiceMesh Data-Plane • 只替换/重启Sidecar • 替换/重启过程中进/出不会出现请求失败，连接失败 • 易于运维，可以控制升级策略 理想的Sidecar升级 envoyproxy.io/docs/envoy/latest/intro/arch_overview/operations/hot_restart https://blog.envoyproxy.io/envoy-hot-restart-1d16b14555b5 实现热升级 Implement Hot-Upgrade 6 • Sidecar生命周期管理能力 • 启动两个Sidecar，以进行Envoy热重启的排水流程两个实例并存的阶段

that boundary using python binding ● Try putting “hot path” code inside your library ○ Need to design a DSL for the user to be able to leverage your hot path capabilities written in C++ ○ Numpy / Pandas provide “hot path” C++ functionsWhat Functions to expose in the API ● Init some data structures / load some data ● Configure your class’ parameters ● Do a lot of complex work inside a “hot path” ● [this]() { return internals_->subscribe(listener); } ); }Example 3 Optimizing python hot loops using *Some analysis code reader = mod.RowReader(f) rows = reader.getRows()

cost too much CPU #4071 – Fix the data race issue that might occur when setting configurations of hot Region scheduler #4159 – Fix slow leader election caused by stucked Region syncer #3936 • TiFlash The KV request duration 99 in TiKV. If you find nodes with a long duration, check whether there are hot spots, or whether there are nodes with poor performance. 6.5.1.6 PD TSO Wait Duration Figure 38: . �→ hot �→ - �→ region �→ - �→ schedule �→ - �→ limit �→ The num- ber of hot Re- gion schedul- ing tasks per- formed at the same time 341 Configuration item Description schedule �→ . �→ hot �→ - �→

features #26333 • PD – Add more QPS dimensions for hot Region scheduling, and support adjusting the priority of the scheduling #3869 – Support hot Region balance scheduling for the write hotspot of TiFlash The KV request duration 99 in TiKV. If you find nodes with a long duration, check whether there are hot spots, or whether there are nodes with poor performance. 6.5.1.6 PD TSO Wait Duration Figure 38: Description schedule �→ . �→ hot �→ - �→ region �→ - �→ schedule �→ - �→ limit �→ The num- ber of hot Re- gion schedul- ing tasks per- formed at the same time schedule �→ . �→ hot �→ - �→ region �→ - �→ cache

from matplotlib import pyplot as plt # 绘图工具 from utils import plot_image, plot_curve, one_hot # 便捷绘图函数 batch_size = 512 # 批大小 # 训练数据集,自动从网络下载 MNIST 数据集，保存至 mnist_data 文件夹 train_db=torchvision 一般把这种编码方式叫作 One-hot 编码(独热编码)。以图 3.7 中的“猫狗鱼鸟”识别系统为 例，所有的样本只属于“猫狗鱼鸟”4 个类别中其一，假设将第1~4号索引位置分别表示 猫狗鱼鸟的类别，那么对于所有猫的图片，它的数字编码为 0，One-hot 编码为[1,0,0,0]； 对于所有狗的图片，它的数字编码为 1，One-hot 编码为[0,1,0,0]，以此类推。One-hot 编码 方式在分类问题 图 3.7 猫狗鱼鸟系统 one-hot 编码示意图 手写数字图片的总类别数有 10 种，即输出节点数?out = 10，那么对于某个样本，假 设它属于类别?，即图片的中数字为?，则只需要一个长度为 10 的向量?，向量?的索引号为 ?的元素设置为 1，其它位为 0。比如图片 0 的 One-hot 编码为[1,0,0,… ,0]，图片 2 的 One- hot 编码为[0,0,1, … ,0]，图片