Solr consistency and recovery internals

Jul 19, 2017Download as pptx, pdf4 likes2,239 views

How does SolrCloud ensure that replicated data remains consistent? How does Solr avoid data loss when hardware inevitably fails? In this talk, we will cover how Solr addresses failures and what recovery steps the cluster can automatically perform.

1© Cloudera, Inc. All rights reserved.
Solr consistency and recovery internals
Mano Kovacs | July 13, 2017

2© Cloudera, Inc. All rights reserved.
Intro
• Mano Kovacs
• Cloudera Search engineer
• Working on “Why is my Solr cluster down?” mysteries.
• 15 yrs of dev, high-performant web services, IoT platform
• Amature slideshow enthusiast

3© Cloudera, Inc. All rights reserved.
Agenda
• Consistency basics (leaders/follower)
• Leader election
• When to recover
• General recovery (peersync, replication)
• Recovery in detail
• Leader-Initiated Recovery
• Auto Add Replica

4© Cloudera, Inc. All rights reserved.
Basics
• Shards in collection
• One leader per shard
• Leader gets writes
• Replicates

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Leader Election
• Zookeeper Leader election recipe
• Sequential, ephemeral nodes for each replica
• The order dictates the leader candidates
• First in order becomes leader candidate
• Replicas watch the previous candidate to get notified
• If leader fails, next in line will be the candidate
• Leader candidates follow leader preparation process

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Leader Election - leader candidate
• On restart: waits all replicas to participate (default 3 mins)
• Sync changes from other replicas
• Verify last state ACTIVE if not startup
• If all were DOWN, shard hangs (SOLR-7065)
• Verify there was no error reported (LIR… tbd)

7© Cloudera, Inc. All rights reserved.
What causes Recovery?
• Routine Events
•Add or Move Replica - not having the data
•Restart (upgrade/tuning) - might missed updates
• Not Routine Events
•Server crash
•Leader
•Replica
•Network failure (Lose ZK Connection)
•Replica partitioned: can access ZK, but not the leader

8© Cloudera, Inc. All rights reserved.
Recovery (from 30k fts.)
• Replaying unfinished updates from tlog
• Check if we are synced
• If no, “How much am I behind?”
• If N (def=100) docs or less
• Retrieving delta
• Else
• Replication: pulling full index
• Go ACTIVE

9© Cloudera, Inc. All rights reserved.
Recovery (from 1000 fts.)
• Buffering new updates
• So we won’t get behind over and over
again
• Waiting leader to notice us
• Otherwise we don’t get updates
• Replay buffered updates
• Hopefully replay catches up with
incoming updates

10© Cloudera, Inc. All rights reserved.
Recovery (from 100 fts.)
• Updates are versioned
• Timestamp+counter
• PeerSync: last N updates by version
• Index has fingerprint (hash of doc versions)
• If there is other updates missing,
fingerprint will fail
• Consistency safety net if others fail

11© Cloudera, Inc. All rights reserved.
Leader-Initiated Recovery
• Partitioning Leader from Replica,
but not ZK
• Leader will send recovery requests
to replica (with retries)
• If Replica went down, it will do
normal recovery process anyway
• If replica is partitioned and up, it
will still serve stale reads :(

12© Cloudera, Inc. All rights reserved.
LIR problems - SOLR-9555
• Race condition between LIR and
standard Recovery
• Mike Drob’s patch is almost done
• Solves problem with
partitioned replicas too with ZK
watches

13© Cloudera, Inc. All rights reserved.
AutoAddReplica
• Using shared file system (e.g. HDFS)
• Provides durability
• Instances share index folders
• Move cores to live nodes on failure
• Use same index folder
• Pros
• Durability with rep factor 1
• Handle perm. node loss
• Cons
• Still no HA and read scalability if
using single replica
• Lots of fix from Mark Miller lately

14© Cloudera, Inc. All rights reserved.
Summary
• Details about SolrCloud cluster
• Help to improve!
• PlantUML is cool to document

15© Cloudera, Inc. All rights reserved.
Thank you
E: manokovacs@cloudera.com
T: @manokovacs

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Antimalarial drug Medicinal Chemistry IIIHRUTUJA WAGH

Antimalarial drugs Malaria can occur if a mosquito infected with the Plasmodium parasite bites you. There are four kinds of malaria parasites that can infect humans: Plasmodium vivax, P. ovale, P. malariae, and P. falciparum. - P. falciparum causes a more severe form of the disease and those who contract this form of malaria have a higher risk of death. An infected mother can also pass the disease to her baby at birth. This is known as congenital malaria. Malaria is transmitted to humans by female mosquitoes of the genus Anopheles. Female mosquitoes take blood meals for egg production, and these blood meals are the link between the human and the mosquito hosts in the parasite life cycle. Whereas, Culicine mosquitoes such as Aedes spp. and Culex spp. are important vectors of other human pathogens including viruses and filarial worms, but have never been observed to transmit mammalian malarias. Malaria is transmitted by blood, so it can also be transmitted through: (i) an organ transplant; (ii) a transfusion; (iii) use of shared needles or syringes. Here's a comprehensive overview of **Antimalarial Drugs** including their **classification**, **mechanism of action (MOA)**, **structure-activity relationship (SAR)**, **uses**, and **side effects**—ideal for use in your **SlideShare PPT**: --- ## 🦠 **ANTIMALARIAL DRUGS OVERVIEW** --- ### ✅ **1. Classification of Antimalarial Drugs** #### **A. Based on Stage of Action:** * **Tissue Schizonticides**: Primaquine * **Blood Schizonticides**: Chloroquine, Artemisinin, Mefloquine * **Gametocytocides**: Primaquine, Artemisinin * **Sporontocides**: Pyrimethamine #### **B. Based on Chemical Class:** | Class | Examples | | ----------------------- | ------------------------ | | 4-Aminoquinolines | Chloroquine, Amodiaquine | | 8-Aminoquinolines | Primaquine, Tafenoquine | | Artemisinin Derivatives | Artesunate, Artemether | | Quinoline-methanols | Mefloquine | | Biguanides | Proguanil | | Sulfonamides | Sulfadoxine | | Antibiotics | Doxycycline, Clindamycin | | Naphthoquinones | Atovaquone | --- ### ⚙️ **2. Mechanism of Action (MOA)** | Drug/Class | MOA | | ----------------- | ----------------------------------------------------------------------- | | **Chloroquine** | Inhibits heme polymerization → toxic heme accumulation → parasite death | | **Artemisinin** | Generates free radicals → damages parasite proteins | | **Primaquine** | Disrupts mitochondrial function in liver stages | | **Mefloquine** | Disrupts heme detoxification pathway | | **Atovaquone** | Inhibits mitochondrial electron transport | | **Pyrimethamine** | Inhibits dihydrofolate reductase (

Chemistry of Warfare (Chemical weapons in warfare: An in-depth analysis of cl...Professional Content Writing's

This presentation provides a comprehensive overview of Chemical Warfare Agents (CWAs), focusing on their classification, chemical properties, and historical use. It covers the major categories of CWAs nerve agents, blister agents, choking agents, and blood agents highlighting notorious examples such as sarin, mustard gas, and phosgene. The presentation explains how these agents differ in their physical and chemical nature, modes of exposure, and the devastating effects they can have on human health and the environment. It also revisits significant historical events where these agents were deployed, offering context to their role in shaping warfare strategies across the 20th and 21st centuries. What sets this presentation apart is its ability to blend scientific clarity with historical depth in a visually engaging format. Viewers will discover how each class of chemical agent presents unique dangers from skin-blistering vesicants to suffocating pulmonary toxins and how their development often paralleled advances in chemistry itself. With concise, well-structured slides and real-world examples, the content appeals to both scientific and general audiences, fostering awareness of the critical need for ethical responsibility in chemical research. Whether you're a student, educator, or simply curious about the darker applications of chemistry, this presentation promises an eye-opening exploration of one of the most feared categories of modern weaponry. About the Author & Designer Noor Zulfiqar is a professional scientific writer, researcher, and certified presentation designer with expertise in natural sciences, and other interdisciplinary fields. She is known for creating high-quality academic content and visually engaging presentations tailored for researchers, students, and professionals worldwide. With an excellent academic record, she has authored multiple research publications in reputed international journals and is a member of the American Chemical Society (ACS). Noor is also a certified peer reviewer, recognized for her insightful evaluations of scientific manuscripts across diverse disciplines. Her work reflects a commitment to academic excellence, innovation, and clarity whether through research articles or visually impactful presentations. For collaborations or custom-designed presentations, contact: Email: professionalwriter94@outlook.com Facebook Page: facebook.com/ResearchWriter94 Website: professional-content-writings.jimdosite.com

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Liquid water was abundant on Mars during the Noachian and Hesperian periods but vanished as 17 the planet transitioned into the cold, dry environment we see today. It is hypothesized that much 18 of this water was either lost to space or stored in the crust. However, the extent of the water 19 reservoir within the crust remains poorly constrained due to a lack of observational evidence. 20 Here, we invert the shear wave velocity structure of the upper crust, identifying a significant 21 low-velocity layer at the base, between depths of 5.4 and 8 km. This zone is interpreted as a 22 high-porosity, water-saturated layer, and is estimated to hold a liquid water volume of 520–780 23 m of global equivalent layer (GEL). This estimate aligns well with the remaining liquid water 24 volume of 710–920 m GEL, after accounting for water loss to space, crustal hydration, and 25 modern water inventory.

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History Discovered: 1900s by Gerhard Domagk; prontosil identified as antibacterial. Mechanism: Prodrug prontosil converts to sulfanilamide—the active antibacterial agent. Developments: Led to drugs like sulfapyridine (1938), sulfacetamide (1941), etc. ⚗️ Chemistry Amphoteric compounds, weak acids (pKa: 4.79–8.56). Solubility increases in alkaline pH. Structural Designations: N4 (para-amino), N1 (sulfonamide NH). N1 substitution: systemic action; N4: gut action. 🧪 Structure–Activity Relationship (SAR) Sulphanilamide core is essential. N4 amino group = modifiable (for prodrugs). Activity depends on: Substitution at N1 Unsubstituted benzene ring Para-positioned amino group Electron-donating heterocycles ↑ activity 📚 Classification Based on Duration: Extra-long acting: Sulphasalazine, Sulphalene Long acting: Sulphadoxine, Sulphamethoxydiazine Intermediate: Sulphamethoxazole Short acting: Sulphamethiazole Injectables: Sulphadiazine, Sulphamethoxine Based on Structure: N-substituted: Sulphadiazine, Sulphacetamide N4-substituted (Prodrugs): Prontosil N1 & N4-substituted: Succinyl sulphathiazole Miscellaneous: Mefenide sodium ⚙️ Mechanism of Action (MOA) Structural analogs of PABA, inhibit folic acid synthesis. Block dihydropteroate synthase → inhibit DNA/RNA synthesis in bacteria. 💊 Uses Infections: UTIs, dysentery, burns, conjunctivitis, meningitis, malaria. Special cases: IBD: Sulfasalazine Burns: Silver sulfadiazine Malaria: Sulfadoxine + Pyrimethamine (resistant P. falciparum) 🧬 Folate Reductase Inhibitors Trimethoprim: DHFR inhibitor, synergistic with sulphonamides. ⚠️ Side Effects Hypersensitivity, crystalluria, nausea, vomiting, hemolytic anemia, kernicterus in neonates.

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Synthetic antifungals Broad spectrum Fungistatic or fungicidal depending on conc of drug Most commonly used Classified as imidazoles & triazoles 1) Imidazoles: Two nitrogens in structure Topical: econazole, miconazole, clotrimazole Systemic : ketoconazole Newer : butaconazole, oxiconazole, sulconazole 2) Triazoles : Three nitrogens in structure Systemic : Fluconazole, itraconazole, voriconazole Topical: Terconazole for superficial infections Fungi are also called mycoses Fungi are Eukaryotic cells. They possess mitochondria, nuclei & cell membranes. They have rigid cell walls containing chitin as well as polysaccharides, and a cell membrane composed of ergosterol. Antifungal drugs are in general more toxic than antibacterial agents. Azoles are predominantly fungistatic. They inhibit C-14 α-demethylase (a cytochrome P450 enzyme), thus blocking the demethylation of lanosterol to ergosterol the principal sterol of fungal membranes. This inhibition disrupts membrane structure and function and, thereby, inhibits fungal cell growth. Clotrimazole is a synthetic, imidazole derivate with broad-spectrum, antifungal activity Clotrimazole inhibits biosynthesis of sterols, particularly ergosterol an essential component of the fungal cell membrane, thereby damaging and affecting the permeability of the cell membrane. This results in leakage and loss of essential intracellular compounds, and eventually causes cell lysis.

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A urinary tract infection (UTI) is an infection of your urinary system. This type of infection can involve your: Urethra (urethritis). Kidneys (pyelonephritis). Bladder (cystitis). Urine (pee) is a byproduct of your blood-filtering system, which your kidneys perform. Your kidneys create pee when they remove waste products and excess water from your blood. Pee usually moves through your urinary system without any contamination. However, bacteria can get into your urinary system, which can cause UTIs. Microorganisms — usually bacteria — cause urinary tract infections. They typically enter through your urethra and may infect your bladder. The infection can also travel up from your bladder through your ureters and eventually infect your kidneys. Urinary tract antiinfective agents are highly active against most of the Gram–negative pathogens including Pseudomonas aeruginosa and Enterobacteria. Newest fluoroquinolone like Levofloxacin are active against Streptococcus pneumonia. Fluoroquinolones are used to treat upper and lower respiratory infections, gonorrhea, bacterial gastroenteritis, skin and soft tissue infections. Types: Based on location Cystitis or Lower UTI (bladder): Symptoms from a lower urinary tract infection include pain with urination, frequent urination, and feeling the need to urinate despite having an empty bladder. You might also have lower belly pain and cloudy or bloody urine. Pyelonephritis or Upper UTI (kidneys): This can cause fever, chills, nausea, vomiting, and pain in your upper back or side. Urethritis(urethra): This can cause a discharge and burning when you pee. Causative Agents: The most common cause of infection is Escherichia coli, though other bacteria or fungi may sometimes be the cause. First generation quinolones are effective against certain gram negative bacteria (e.g. Shigella, E. Coli) and ineffective against gram positive organisms Second generation quinolones are effective against gram positive and gram negative organisms including Enterobacteriaceae, Pseudomonas, Neisseria, Haemophilus, Campylobacter and Staphylococci General Uses: UTI, Gonorrhea, Bacterial gastroenteritis, Typhoid, RTI, Soft tissue infection, and tuberculosis ADR: It may damage growing cartilage and cause an arthropathy

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Solr consistency and recovery internals

2. 2© Cloudera, Inc. All rights reserved. Intro • Mano Kovacs • Cloudera Search engineer • Working on “Why is my Solr cluster down?” mysteries. • 15 yrs of dev, high-performant web services, IoT platform • Amature slideshow enthusiast

3. 3© Cloudera, Inc. All rights reserved. Agenda • Consistency basics (leaders/follower) • Leader election • When to recover • General recovery (peersync, replication) • Recovery in detail • Leader-Initiated Recovery • Auto Add Replica

5. 5© Cloudera, Inc. All rights reserved. Leader Election • Zookeeper Leader election recipe • Sequential, ephemeral nodes for each replica • The order dictates the leader candidates • First in order becomes leader candidate • Replicas watch the previous candidate to get notified • If leader fails, next in line will be the candidate • Leader candidates follow leader preparation process

6. 6© Cloudera, Inc. All rights reserved. Leader Election - leader candidate • On restart: waits all replicas to participate (default 3 mins) • Sync changes from other replicas • Verify last state ACTIVE if not startup • If all were DOWN, shard hangs (SOLR-7065) • Verify there was no error reported (LIR… tbd)

7. 7© Cloudera, Inc. All rights reserved. What causes Recovery? • Routine Events •Add or Move Replica - not having the data •Restart (upgrade/tuning) - might missed updates • Not Routine Events •Server crash •Leader •Replica •Network failure (Lose ZK Connection) •Replica partitioned: can access ZK, but not the leader

8. 8© Cloudera, Inc. All rights reserved. Recovery (from 30k fts.) • Replaying unfinished updates from tlog • Check if we are synced • If no, “How much am I behind?” • If N (def=100) docs or less • Retrieving delta • Else • Replication: pulling full index • Go ACTIVE

9. 9© Cloudera, Inc. All rights reserved. Recovery (from 1000 fts.) • Buffering new updates • So we won’t get behind over and over again • Waiting leader to notice us • Otherwise we don’t get updates • Replay buffered updates • Hopefully replay catches up with incoming updates

10. 10© Cloudera, Inc. All rights reserved. Recovery (from 100 fts.) • Updates are versioned • Timestamp+counter • PeerSync: last N updates by version • Index has fingerprint (hash of doc versions) • If there is other updates missing, fingerprint will fail • Consistency safety net if others fail

11. 11© Cloudera, Inc. All rights reserved. Leader-Initiated Recovery • Partitioning Leader from Replica, but not ZK • Leader will send recovery requests to replica (with retries) • If Replica went down, it will do normal recovery process anyway • If replica is partitioned and up, it will still serve stale reads :(

12. 12© Cloudera, Inc. All rights reserved. LIR problems - SOLR-9555 • Race condition between LIR and standard Recovery • Mike Drob’s patch is almost done • Solves problem with partitioned replicas too with ZK watches

13. 13© Cloudera, Inc. All rights reserved. AutoAddReplica • Using shared file system (e.g. HDFS) • Provides durability • Instances share index folders • Move cores to live nodes on failure • Use same index folder • Pros • Durability with rep factor 1 • Handle perm. node loss • Cons • Still no HA and read scalability if using single replica • Lots of fix from Mark Miller lately

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